1 2 Previous Next 69 Replies Latest reply: Mar 13, 2011 6:36 PM by Canned Pug RSS

    How to best color correct image

    Canned Pug Community Member

      Hi,

       

      I earlier asked a question whereas I was having problems with color consistency from PS to ID. After resolving that I've run into another issue:

       

      In trying to figure out a way to put an image in ID in a specific set of red cmyk numbers. I've come up with two solutions, but each has a set of problems. Both are CMYK.

       

      The image on the left is a flattened black and red image (halftone) tif from Photoshop (the filter used flattens it). IT looks pretty god but If I try to adjust it with the correct red numbers, the black isn't neutral and gets a color cast, or I'm afraid it will in the printing process.

       

      The one on the right is a black and transparent tif from Photoshop that has been place over a red background (already in ID). Why does this 2nd one appear to be greyed?

       

      (I think I need to learn to fine-tune the color correction on the left one, but not sure which controls to use).

       

      Thoughts?

       

      Picture 1.png

       

      No sooner did I post this, I read about someone else talking earlier about using the Multiply effect ( I didn't realize you could do this in ID), I tried it  and got a more integrated image which is what I wanted. Neat. Now, are there any printing repercussions during the printing process with this effect that I need to worry about, or WYSIWYG? ( I still need to tweak the contrast I know, but at least the red is right.)

       

      Picture 2.png

        • 1. Re: How to best color correct image
          Jeffrey_Smith Community Member
          Now, are there any printing repercussions during the printing process with this effect that I need to worry about, or WYSIWYG?

          If you are printing 4C process (offset or digital) make sure the red color is not set up as a spot color.

          If you are printing black + spot red, consult your printer for any special file preparations.

          • 2. Re: How to best color correct image
            Canned Pug Community Member

            this red is a process color. Can't use spot colors with this publisher. But what about the image (black/greys). Don't know if this is a spot color or not ...it was initially greyscale then converted to cmyk.

            • 3. Re: How to best color correct image
              rob day Community Member
              Why does this 2nd one appear to be greyed?

               

              The multiply version is effectively overprinting black on the red, so if your red background was something like 0|100|80|0, the gray values become the background plus the black value. So, in the right version 50% black would be  knocking out (0|0|0|50), and in the left version it overprints (0|100|80|50). 0|100|80|50 & 0|0|0|50 are very different colors.

               

              If you want complete control over the image's tonality you could also multiply over in PS where you could apply a curve to the grayscale, something like below where I copied the grayscale into the black channel of a CMYK file (it's important to copy into the channel rather than convert the GS to CMYK), added a red layer beneath and an adjustment layer on top linked to the image layer, which is set to multiply:

               

              PSOP.png

              • 4. Re: How to best color correct image
                Canned Pug Community Member

                Ok getting close here.

                 

                I just did try a multiply in PS, which turned the black cool-ish...actually  I don't know, so it seemed. Went into Adjustment> Hue/Sat and took all the saturation out of the black image (Multiply layer), but couldn't tell if it did anything in terms of neutralizing the blacks.

                Picture 3.png

                 

                (It's been a while using adjustment layers...You do an adjustment layer instead of Image>Adjustment>Curves or Hue/Sat because it isn't permanent? So then you can flatten the file later no problem?

                 

                Not sure what you mean by bringing the scale into the channels. Not sure how to do this..I'm in CS3.

                 

                So you bring in the scale to make sure that if it looks good with the adjustments then the image will have the full tonal range as well?

                 

                so finally, what you're saying in terms of control, you think it best to resolve the image in PS then bring into ID instead of pulling a transparent image one on top of the colored background in ID?

                 

                PS I'd like to be able to open up the areas of blacks so it isn't so muddy but don't want to grey out the blacks. Curves then?

                 

                Thanks so much for the time you're putting into all this.

                • 5. Re: How to best color correct image
                  Canned Pug Community Member

                  ...the Curves changes the red color...:o( ??

                  • 6. Re: How to best color correct image
                    Canned Pug Community Member

                    ok, instead of doing the Curves as an adjustment layer, doing it from Image > Adjustments > Curves, will do it just for the one layer ..the other is global on all layers...(whew!)

                    • 7. Re: How to best color correct image
                      rob day Community Member
                      Not sure what you mean by bringing the scale into the channels. Not sure how to do this..I'm in CS3.

                       

                      You need to have the image in the black channel only—your getting the cool cast because if you paste a grayscale into a CMYK file it gets converted into all 4 CMYK channels.

                       

                      The sequence I used starting with a flattened grayscale was:

                      Select All>Cut>ModeCMYK>click the Black Channel in the Channels panel>Paste. Then I double-click the background to make it Layer 0>set it to Multiply>created a color layer beneath and an adjustment layer above and made the adjustment layer aclipping mask so it doesn't affect the red (Layer>Create Clipping Mask).

                       

                      You do an adjustment layer instead of Image>Adjustment>Curves or Hue/Sat because it isn't permanent?

                       

                      Yes. You don't need to flatten it, just place it in ID with the layers.

                       

                      Here's my example file:

                       

                      http://www.zenodesign.com/forum/multiplyPS.zip

                      • 8. Re: How to best color correct image
                        rob day Community Member
                        ok, instead of doing the Curves as an adjustment layer, doing it from Image > Adjustments > Curves, will do it just for the one layer

                         

                        Make the adjustment layer a Clipping Mask. Option-Click the line between the layers or with the adjustment layer selected choose Layer>Create Clipping Mask.

                        • 9. Re: How to best color correct image
                          Canned Pug Community Member

                          OK re: clipping mask.

                           

                          What do you mean by "greyscale", are you talking about the calibration strip? and/or the car?

                           

                          I'm going one question at a time because your answer raised many...

                          • 10. Re: How to best color correct image
                            rob day Community Member

                            I meant the color mode of the starting image. Open the image you want to multiply and make sure it's a flattened Grayscale (Image>Mode>Grayscale) then follow the sequence in post 7. This is more complicated than simply placing a Grayscale in ID and multiplying it over a color—all it gets you is the ability to adjust brightness and contrast relative to the background in real time. You don't have to use Curves, it could be Levels or Brightness & Contrast.

                            • 11. Re: How to best color correct image
                              Canned Pug Community Member

                              Ok, got that. And I've started over with my greyscale image. I've managed to paste it into the black channel. Was able to duplicate adjustment layer w a clipping mask.

                               

                              Again, what is assuring no cast to the black is that it's in the black channels layer? Will this change then with various file color profiles? I've got mine set to the one recommended by the publisher.

                               

                              So this is what my channels looks like...hope it's right. This is a wonderful lesson.

                               

                              Picture 2.png

                               

                              I noticed that your adjustment layer widens the range of values on the calibration strip. I'm sure one doesn't need the strip but using it really shows the difference.

                               

                              I have a calibration strip in B&W in RBG mode. Could I use this by bringing it into the other file?  should I change the mode on it to greyscale first? Becasue I know I could make an adjustment layer without it and eyeball it but my image is not very good to start with, maybe it would help my eye?

                              • 12. Re: How to best color correct image
                                rob day Community Member
                                Again, what is assuring no cast to the black is that it's in the black channels layer? Will this change then with various file color profiles? I've got mine set to the one recommended by the publisher.

                                 

                                There can't be a cast because the image is only on the black plate—your background color could change depending on the ink balance on press, or the image might get lighter or darker depending on how much black is running.

                                 

                                Will this change then with various file color profiles?

                                 

                                The CMYK profile affects the preview in both PS and ID—you just want to make sure you don't have conflicting profiles, the assignment should be the same in both programs. When you export make sure the destination is Document CMYK, which it is by default.

                                 

                                should I change the mode on it to greyscale first?

                                 

                                If you paste a Grayscale into your CMYK file it will convert to all four plates, so you would need to run it through the sequence before pasting into CMYK—flatten>Select All>Cut>CMYK>Black Channel Paste>then copy and paste into your CMYK file. If you're going to do it a lot make an action.

                                • 13. Re: How to best color correct image
                                  Canned Pug Community Member

                                  Excellent. This has been really helpful and helped me understand what is going on. Thanks for your time once again Rob.

                                   

                                  (btw, how are you all  able to isolate parts of questions..sort of looks like a screen shot, but looks different as it's a consistant width, as below?)

                                   

                                  Picture 3.png

                                  • 14. Re: How to best color correct image
                                    rob day Community Member

                                    Copy and paste the text you want to show as a quote, select it, and click the Quote Previous Message icon (top row far right)

                                     

                                     

                                    • 15. Re: How to best color correct image
                                      Canned Pug Community Member
                                      Copy and paste the text you want to show as a quote, select it, and click the Quote Previous Message icon (top row far right)

                                       

                                      ah, like this? neat.

                                      • 16. Re: How to best color correct image
                                        Canned Pug Community Member
                                        Select All>Cut>ModeCMYK>click the Black Channel in the Channels panel>Paste. Then I double-click the background to make it Layer 0>

                                         

                                        I was able to paste the strip into the black channel :

                                        Picture 1.png

                                         

                                        but when I double-clicked on the layer to make it layer 0,  this happened and it's not on Multiply:

                                        Picture 2.png

                                         

                                        I put it on Multiply and added a layer filled with white but no change. What am I not getting now?

                                        • 17. Re: How to best color correct image
                                          rob day Community Member

                                          I can see you have values in the CMY channels—the background of the CMYK file needs to be white before you paste into the Black channel.

                                          • 18. Re: How to best color correct image
                                            Canned Pug Community Member

                                            There, thanks:

                                             

                                            Picture 1.jpg

                                            • 19. Re: How to best color correct image
                                              Canned Pug Community Member

                                              so then all these other types of images I may have to redo. I was given this other process from a Blurbian with which to neutralize my black and clear (transparent) images..they seem ok over the light creme background, but when brought inot the darker red bg it wasn't working

                                               

                                              I do notice color in the other channels: Looks good but could look better. Some of these images responded to Multiply, others did not that I could see. I'm probably going to rework them

                                              Picture 2.png

                                              This process was given to me by a photogrqapher  in the Blurb forum who seem very happy with the books she's made, and created her own way to process B&W images rather than use Blurb's recommendations as she had made test booklets and wasn't so happy with them

                                               

                                              I'm running your process by her to see what she thinks,,,but then she's not using transparent images. I think saving into the black channel is pretty clever myself.

                                              • 20. Re: How to best color correct image
                                                Canned Pug Community Member

                                                so my previous channels screenshot wasn't right either as there are values in the channels palette as well. (#11 post.)

                                                • 21. Re: How to best color correct image
                                                  rob day Community Member

                                                  If you decide the Photoshop method is worth the extra work you'll want to record an action. For files that have already been converted to CMYK the best approach will probably be to flatten and convert to Grayscale then run the sequence—unless you have access to the original Grayscales. Also, if you use PS you'll need to be very careful that the CMYK files don't get converted to some other CMYK space on export—use PDF/x-1a.

                                                  • 22. Re: How to best color correct image
                                                    Canned Pug Community Member

                                                    I've been given profiles to work in and save, and the export given is this:

                                                     

                                                    Based on 'Blurb PDF X-3 Export Preset'] [Based on '[PDF/X-3:2002]'] Use these settings to create Adobe PDF documents that are to be checked or must conform to PDF/X-3:2002, an ISO standard for graphic content

                                                     

                                                    I could create an action but as each photo is different re: density and some need more sharpening than others (as many have come from crummy and small 72 dpi images, and they would have to be handled differently within adjustments, etc...?

                                                    • 23. Re: How to best color correct image
                                                      rob day Community Member

                                                      Just be aware that PDF/X-3 allows CMYK-toCMYK conversions downstream. If everyone's using the same CMYK profile—you're not introducing conflicting profiles anywhere, and the printer uses the same profile at output—then it's not a problem. If there's a CMYK-to-CMYK conversion anywhere in the workflow, the layer PS approach no longer works.

                                                       

                                                      An action will be useful to set up the 3 layers. You'll still need to manually edit the adjustment layer.

                                                      • 24. Re: How to best color correct image
                                                        Canned Pug Community Member
                                                        If everyone's using the same CMYK profile—

                                                         

                                                        You mean file profiles or PDF export profiles? They're giving you peramters for both so I'm assuming it should be consistant:

                                                         

                                                        Files: Blurb_ICC_Profile.icc

                                                        Export:  (as in above post) Blurb PDF X-3 Export (Preset v1-1)

                                                         

                                                        They do allow other SWOP profiles as well, but I'm going to use just one profile for all my artwork, both B & W and Color.

                                                        • 25. Re: How to best color correct image
                                                          Canned Pug Community Member

                                                          oh, and they allow you to submit images as sRBG and the printer will 

                                                          convert but I'm not doing that as there will be a color shift and I 

                                                          want to see it beforehand.

                                                          • 26. Re: How to best color correct image
                                                            Canned Pug Community Member

                                                            and also, when I went to place my calibration strip into my image, it said the "depths" (bit) were different and I may get a lower quality, but that wouldn't affect the values would it just the resampling, that sort of thing? Shouldn't matter? I changed the dpi's to match but still got the same message but assumed the above.

                                                            • 27. Re: How to best color correct image
                                                              rob day Community Member
                                                              You mean file profiles or PDF export profiles?

                                                               

                                                              Both.

                                                               

                                                              If you use the Blurb_ICC_Profile.icc profile consistently throughout your work flow and export to PDF/X-3 using Document CMYK as the destination, that profile will be included with your PDF. That works if the Blurb_ICC_Profile is used as the output profile by the printer. If they were to use US SWOP your CMYK values would get converted.

                                                               

                                                              The only difference in the PDF/X-1a preset is when you export any objects not in the Blurb_ICC_Profile CMYK space will be converted to Blurb_ICC_Profile CMYK space and the profile will not be included in the PDF making it difficult to get or force an unwanted conversion at output.

                                                               

                                                              If you do use PDF/X-3 make it clear that you want you CMYK values output unchanged when you send the job.

                                                              • 28. Re: How to best color correct image
                                                                rob day Community Member
                                                                when I went to place my calibration strip into my image, it said the "depths" (bit) were different and I may get a lower quality,

                                                                 

                                                                The strip is probably saved as 16-bit. The only time 16-bit is needed in a print workflow is if you are constantly applying color corrections to a flattened image and dropping gray levels in the process. With adjustment layers that's not a problem. You can safely ignore the message.

                                                                • 29. Re: How to best color correct image
                                                                  Canned Pug Community Member

                                                                  In other words, they let clients use another cmyk SWOP profile and didn't  converted and this client loved the outcome better, as she had run a test book with Blurb's B&W instructions and didn't like it. (*She's a B&W photographer).

                                                                   

                                                                  I think the publishers just convert the sRGB's.

                                                                   

                                                                  *She was showing me her workflow because she wasn't happy with the way Blurb had people set up their B&W images. Not sure how she arrived at it but I had many conversations with her, liked her reasoning and did all my B&W with her profile. Now I may just use your way as it seems the blacks would be even more neutral. At least there are a few different methods to choose from. I'd be really surprised if my first book came out right anyway, so we'll see.

                                                                   

                                                                  Many ways to skin a cat.

                                                                   

                                                                  ok re: calibration strip. Thanks.

                                                                   

                                                                   

                                                                  If you're interested in her method, here is a link:

                                                                   

                                                                  http://forums.blurb.com/forums/10/topics/8249

                                                                   

                                                                   

                                                                  • 30. Re: How to best color correct image
                                                                    rob day Community Member
                                                                    If you're interested in her method, here is a link

                                                                     

                                                                    Her method is basically correct for straight grayscale to CMYK conversions. In general profiles designed for color work have a light black plate, which is good for saturated color but bad for neutral CMYK "quadtones". The point of running Grayscales as CMYK quadtones is to get more dynamic range (adding CMY to extend the black end of the scale). Limiting the total ink to 240 and the UCA to 0 almost defeats the purpose because there will be very little CMY underneath.

                                                                     

                                                                    A heavy black conversion doesn't work in your case because you want a saturated red in the CMY channels—building the file in layers should be better.

                                                                    • 31. Re: How to best color correct image
                                                                      Canned Pug Community Member

                                                                      Thank you, you are so helpful.

                                                                       

                                                                      ...from Miickii's iiPhone

                                                                      • 32. Re: How to best color correct image
                                                                        Canned Pug Community Member

                                                                        Rob,

                                                                         

                                                                        I wouldn't hold you responsible  but would like your opinion: Would 

                                                                        you recommend I continue using her workflow (SWOP) as I already have 

                                                                        for this type of artwork (below) or yours? These pieces are tifs on 

                                                                        transparent backgounds so they pick up the color of the background, 

                                                                        rather than flattening on a bg of the same color.... I need it to 

                                                                        blend seamlessly using the pages of the book as the "whites" in the 

                                                                        photos and I don't want to risk the color even being a step off. I'm 

                                                                        asking becasue I'm wondering if the blacks and greys will be similar 

                                                                        in density and neutrality (no color cast) as in your technique. I put 

                                                                        the image on "Multiply" in ID and it doesn't seem to change 

                                                                        anything...so maybe that's a good thing. Thanks! (think forum is down 

                                                                        for a while):::

                                                                        • 33. Re: How to best color correct image
                                                                          rob day Community Member
                                                                          I continue using her workflow (SWOP)

                                                                           

                                                                          What profile are you assigning to your images and ID doc?

                                                                           

                                                                          If you use the SWOP profile in your workflow, then export to PDF/X-3, the SWOP profile is going to get embedded into your exported PDF. That's fine if the printer outputs to SWOP as the destination profile. But it sounds like the printer is providing a profile for their presses Blurb_ICC_Profile.icc, so I would assume they will output to that profile, which will convert objects profiled with SWOP into their profile. If you want to control the CMYK values in your file you have to assign their output profile, or export to PDF/X-1a.

                                                                           

                                                                           

                                                                          I need it to blend seamlessly using the pages of the book as the "whites" in the photos and I don't want to risk the color even being a step off.

                                                                           

                                                                           

                                                                          If you are multiplying black & white (grayscale) images over a color, converting them to CMYK first—even with a heavy black plate—doesn't get you anything. The advantage of adding CMY to the black end of the scale goes away because the underneath color is being added to the blacks. If you already have converted your images to the heavy black CMYK I doubt it will be a disaster, but it's less flexible than the other two options when you need to color correct.

                                                                          • 34. Re: How to best color correct image
                                                                            rob day Community Member

                                                                            This illustrates the difference in multiplying a heavy black CMYK mix vs. 50% black—the top version does have the potential to slightly cast if the cyan is high or low:

                                                                             

                                                                            cmykvgsmulti.png

                                                                            • 35. Re: How to best color correct image
                                                                              Canned Pug Community Member

                                                                              I just wrote a huge, even more convoluted post trying to answer your questions, which I'll save for later because it may be moot. I'm thinking aloud here to try to clarify:

                                                                               

                                                                              We'er talking about 2 issues here, the greyness of the blacks and how they look on the surface and the color cast that may occur, is that right?

                                                                               

                                                                              Let me say that I initially used a 3rd party filter called "Ghost" (can only be used on RGB images). I use it on B&W images as well as color. That takes out all white information and leaves all transparency in various densities. Only a solid black has no transparency. Then I converted to Robin's SWOP Heavy. She is using black & white photos, not transparent images.

                                                                               

                                                                              Then came along your process.

                                                                               

                                                                              I took those images that were over cream (in Robin's workflow...I didn't see anything wrong with these images intially), then put them over red and sure enough got that greyed-out look, which is only noticable over red, but if I use them may show up in print that way, which leads me to believe I need to use your process, as the quality of the blacks needs to be consistant.

                                                                               

                                                                              Left is Robin's profile, right side is with "Multiply" applied. Which leads me to believe that I need to re-do all my images as per your ideas. I thought black would be black. Guess not.  I'm not sure if the end result of using your process is the same as using multiply or not but it looks the same and is consistant.

                                                                              Picture 5.png

                                                                               

                                                                              All that being said, what again should be my images profiles and ID file be?

                                                                               

                                                                              this is what they are, ..and I thought they were Blurb's but I screwed something up there too...

                                                                               

                                                                              Images..don't remember If I need to convert!!? I think so then what's the point? UGH:

                                                                              Picture 2.png

                                                                               

                                                                              ID file:

                                                                              Picture 4.png
                                                                              Picture 3.png
                                                                              • 36. Re: How to best color correct image
                                                                                rob day Community Member

                                                                                That takes out all white information and leaves all transparency in various densities. Only a solid black has no transparency. Then I converted to Robin's SWOP Heavy. She is using black & white photos, not transparent images.

                                                                                 

                                                                                You don't need transparency if you are multiplying. You can use a flattened grayscale multiplied in ID and get the effect you are looking for—white multiplied over 0|100|80|0 doesn't change the color.

                                                                                 

                                                                                With either method—multiplying a grayscale in ID, or building a layered file in PS—you need to start with a grayscale. So you don't want to convert to a CMYK space, just convert to Grayscale via Image>Mode>Grayscale.

                                                                                 

                                                                                Also make sure your Transparency Blend Space is set to CMYK in ID.

                                                                                • 37. Re: How to best color correct image
                                                                                  Canned Pug Community Member

                                                                                  ok good, thanks, and thanks for the info re Trans Blend Space..something I still had to research...

                                                                                  • 38. Re: How to best color correct image
                                                                                    zaconda Community Member

                                                                                    Always start with the grayscale image and the contrast you want to portray.  Overlaying the red in indesign is your choice it doesn't really matter how you do it. You will end up flat or contrasty depending on your interpretation. You can look too far into the finer points with some tweaking but as with most things simplicity is the key.

                                                                                    Don't go overboard. I have seen people create something which they believe is commercially acceptable and I would not feed it to my dog. I have had 30 years experience with the print and pre press industry and believe me some designers go over the top trying to acheive something that will never happen.

                                                                                    • 39. Re: How to best color correct image
                                                                                      Canned Pug Community Member

                                                                                      yes, and at this point it has snowballed into a workflow I can't differentiate. I was  trying to create a workflow that would work becasue the more I read the more I thought I have to do this and I have to do that, then different people do things that make sense so I try to do that.

                                                                                      I was really following blindly, but not understanding the whys.

                                                                                       

                                                                                      I think all the ideas presented are good ones that work for who is using them. I just don't know what right for me or how they relate to what I really need

                                                                                       

                                                                                      thanks though to remind me to keep it simple, as I can never see the forest for the trees. I just see more and more variables, not sure which are important and which should be left for another day. Everyone has been so kind and helpful though.

                                                                                       

                                                                                      My dog would eat it all and not know the differences anymore than me!

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