23 Replies Latest reply on Jan 23, 2010 10:24 AM by shunithD

    White background causes colour shift

    shunithD Level 3

      Ran into a bit of a strange problem... am sure there's a simple explanation...

       

      Gradient or solid colour in the blue range set at 40% transparency

       

      1/ When placed on a blank surface (no background) looks ok

      2/ When placed over an underlying white background gets a magenta tinge

       

      Questions:

       

      1/ Which is the true colour?

      2/ What will i get when printing by offset?

       

      3/ The following seem to be the affected / effects:

      a/ CMYK Red (0, 100, 100, 0)

      b/ CMYK Yellow (0, 0, 100, 0) - NO effect

      c/ CMYK Green (100, 0, 100, 0)

      d/ CMYK Cyan (100, 0, 0, 0)

      e/ CMYK Blue (100, 100, 0, 0)

      f/ CMYK Magenta (0, 100, 0, 0) - looks paler

       

      Attaching a test file...

       

      Edit: Here's the jpgtest.jpg

        • 1. Re: White background causes colour shift
          Jacob Bugge MVP & Adobe Community Professional

          SD,

           

          The reason seems to be that the Groups to which the coloured rectangle belongs have 40 transparencies, so in effect, the colour gets deluted twice, a bit like whitewashing.

           

          Said with the reservation of my opening the document in 10.

          • 2. Re: White background causes colour shift
            shunithD Level 3

            Jacob Bugge wrote:

             

            The reason seems to be that the Groups to which the coloured rectangle belongs have 40 transparencies, so in effect, the colour gets deluted twice, a bit like whitewashing.

             

            Said with the reservation of my opening the document in 10.

            Jacob... a bit confused by your reply...

             

            1/ Transparency set to 40%... that's it

             

            The two patches are independent. The top half of each patch is on a 'blank' background. The bottom half is on top of a white background

             

            Cheers,

             

            Shunith

             

            Edit: Sorry, should have mentioned at the outset: AI CS4 on Win XP

            • 3. Re: White background causes colour shift
              Jacob Bugge MVP & Adobe Community Professional

              SD,

               

              If you look in the Layers panel, the blue rectangle is nested in two groups, each of which has a 40 transparency; since it is at group level(s), the transparency also has effect on the rectangle. You should see a change to normal (saturation) if you Ungroup twice.

               

              Edit: This is strange: I was sure I read in in the OP that it was CS4; but at least I knew it was newer than 10 when I imported the document.

              • 4. Re: White background causes colour shift
                shunithD Level 3

                Jacob Bugge wrote:

                 

                If you look in the Layers panel, the blue rectangle is nested in two groups, each of which has a 40 transparency; since it is at group level(s), the transparency also has effect on the rectangle. You should see a change to normal (saturation) if you Ungroup twice.

                 

                Edit: This is strange: I was sure I read in in the OP that it was CS4; but at least I knew it was newer than 10 when I imported the document.

                Jacob...

                 

                There are no groups. The structure, in descending order, is as follows:

                 

                1 or base layer/ Name: White patch

                –> Path (a white rectangle that partially underlays the layer above)

                 

                2 layer on top / Name: gradient with transparency – this has two sub-layers

                –> Path (a blue rectangle with 40% transparency)

                –> Path (a blue-based gradient with 40% transparency)

                 

                Each of the 'paths' – in 2 above – are partly overlaid over no background (upper half) and on a white background (lower half)

                • 5. Re: White background causes colour shift
                  Jacob Bugge MVP & Adobe Community Professional

                  Ah, SD.

                   

                  This seems to show that it may be quite impossible to see what is in the file when opening it in an earlier version:

                   

                  When opened in 10 Layer 1 contains (with transparencies):

                   

                  Group: 100%

                       Clipping Path

                       Group: 40%

                            Group: 40%

                                 Path: 100% (the blue one, to the right)

                            Group: 100%

                                 Path: 40% (the no stroke/no fill one, to the left, no overlap with the blue path, the gradient has simply vanished)

                       Path: 100% (the white one beneath the other paths)

                   

                  As you can see, in the 10 version, there are 2 group levels with transparency over the path.

                   

                  Apart from that, there is no difference in colour of the blue path between the upper and lower parts.

                  • 7. Re: White background causes colour shift
                    shunithD Level 3

                    Well you can see what i'm talking about... the lower halves are a different shade...

                     

                    It's also the same in CS3... am attaching the CS3 version.

                     

                    As i said, the difference is happening where the boxes overlay the white patch below....

                    • 8. Re: White background causes colour shift
                      Jacob Bugge MVP & Adobe Community Professional

                      SD,

                       

                      This time I got the opening message that the file was saved without PDF content; otherwise the file was empty. This shows that what I saw earlier was the PDF part. Funny, the CS3 size is larger.

                       

                      In any case, the artwork structure seems to hold Groups and Clipping Masks, even more complex in the CS3 version screenshot by Peter.

                       

                      Now I am curious to see a screenshot from the original CS4 version.

                       

                      Obviously, there should be no colour shift over a white background so this may be some kind of bug introduced some time after 10, and at least in CS3.

                       

                      It may be worth simplifying the structure (removing Clipping Masks etc) to see where the right colour appears and thereby find out whatactually causes the shift.

                      • 9. Re: White background causes colour shift
                        JETalmage Level 6

                        Don't overcomplicate the problem.

                         

                        1. CMYK document.

                        2. Draw a rectangle filled 0C0M0Y0K.

                        3. Draw a partially overlapping rectangle filled with 100C0M0Y0K.

                        4. Set the Transparency of the cyan rectangle to 50%, Normal mode.

                         

                        I encounter this and the "white-is-pink" problem, which I suspect is associated, frequently in CS3.

                         

                        JET

                        • 10. Re: White background causes colour shift
                          shunithD Level 3

                          Jacob Bugge wrote:

                           

                          This time I got the opening message that the file was saved without PDF content; otherwise the file was empty. This shows that what I saw earlier was the PDF part. Funny, the CS3 size is larger.

                           

                          In any case, the artwork structure seems to hold Groups and Clipping Masks, even more complex in the CS3 version screenshot by Peter.

                           

                          Now I am curious to see a screenshot from the original CS4 version.

                           

                          Obviously, there should be no colour shift over a white background so this may be some kind of bug introduced some time after 10, and at least in CS3.

                           

                          It may be worth simplifying the structure (removing Clipping Masks etc) to see where the right colour appears and thereby find out whatactually causes the shift.

                          Yes... this time i saved without the PDF content... thought the file would be smaller... but was larger!!!

                           

                          There are no clipping masks, etc Jacob.

                           

                          Put simply, a white rectangle (0, 0, 0, 0). Partly overlaying it is a rectangle with a colour swatch set to 40% (or any transparency).  Fill the rectangle with any colour other than yellow. There is a colour shift where it overlays the white.

                          • 11. Re: White background causes colour shift
                            shunithD Level 3

                            JETalmage wrote:

                             

                            Don't overcomplicate the problem.

                            JET,

                             

                            I'm not over-complicating the problem. I'm stating the problem.

                             

                            I think the others are over-complicating it as the original example was a CS4 file which was behaving differently when opened.

                             

                            You seem to be aware of this... as you say:

                             

                            I encounter this and the "white-is-pink" problem, which I suspect is associated, frequently in CS3.

                             

                            So the "white-is-pink", is giving a magenta cast... the questions are;

                             

                            1/ Will this affect a print by four-colour offset?

                             

                            2/ Is there a solution?

                            • 12. Re: White background causes colour shift
                              JETalmage Level 6

                              I don't pretent to understand the "logic" of it, but it is related to the Document Setup option, Simulate Colored Paper:

                               

                               

                              I'm not over-complicating the problem....I think the others are over-complicating it...

                               

                              My comment was not directed specifically at you. It was directed generally to the thread, therefore "addressed" to its originator (I can't do anything about that, it's the way the forum works.)

                               

                              My point is: Far more often than not, users trying to describe a problem here fail to try to boil the issue down to the simplest steps required to duplicate it. Responders fail to do the same and the thread spins off into a confusion of superfluous and spurious unrelated detail.

                               

                              JET

                              • 13. Re: White background causes colour shift
                                Jacob Bugge MVP & Adobe Community Professional

                                SD,

                                 

                                As far as I can see, this means that:

                                 

                                1) There is indeed a bug in CS3/CS4 where funny colour changes may occur, as described here by you, Peter, and James. If it were the same in CS2, I am sure Harron would have told us.

                                 

                                2) There is a complication of the artwork structure when a CS4 document is reinterpreted at its being opened in CS3 or earlier.

                                 

                                10 and CS2 are your friends.

                                 

                                Edit: This was started right after post  #10.

                                 

                                At least I have benefitted from the added knowledge caused by the details, now knowing that funny changes in artwork structure occurs even between CS4 and CS3 which means that there may be reservations to any attempts to replicate issues in other versions, although not in this case.

                                 

                                And it seems that the Simulate Colored Paper option should read: Simulate Colored Paper or perish.

                                • 14. Re: White background causes colour shift
                                  shunithD Level 3

                                  Jacob Bugge wrote:

                                   

                                  10 and CS2 are your friends.

                                   

                                  Jacob...

                                   

                                  The problem has been 'successfully' duplicated in CS2 for the Mac

                                  • 15. Re: White background causes colour shift
                                    shunithD Level 3

                                    JETalmage wrote:

                                     

                                    My point is: Far more often than not, users trying to describe a problem here fail to try to boil the issue down to the simplest steps required to duplicate it. Responders fail to do the same and the thread spins off into a confusion of superfluous and spurious unrelated detail.

                                     

                                    Fair enough, but i don't see how i could have simplified it anymore than i did in all my posts... the confusion, as i see it was arising from others trying to look at the structure of the file as against the problem outlined which they could have as easily tried as you did.

                                     

                                    Anyway, so there is a bug...

                                     

                                    The question now remains is, is this just an optical illusion (meaning visible only on the screen) or is will it translate into print? Have you had any experiences with this?

                                     

                                    If it is the case and, remains a serious issue, then is using 'Simulate Colored Paper On' the only way to resolve the issue?

                                     

                                    And, would one have to modify all artworks going in for printing accordingly?

                                    • 16. Re: White background causes colour shift
                                      Jacob Bugge MVP & Adobe Community Professional

                                      SD,

                                       

                                      And, would one have to modify all artworks going in for printing accordingly?

                                       

                                      Only when Illy starts seeing things (White? It cannot be just white. If you look closely there must be something, just a tinge. Oh there it is: a very very faint pink that no one else can see (who says Illy is not a she?)).

                                      • 17. Re: White background causes colour shift
                                        shunithD Level 3

                                        Jacob Bugge wrote:

                                         

                                        Only when Illy starts seeing things (White? It cannot be just white. If you look closely there must be something, just a tinge. Oh there it is: a very very faint pink that no one else can see (who says Illy is not a she?)).

                                         

                                        Illy.... ???? definitely a woman... pink, as in elephants? Mmmm doubtful... white as in 0, 0, 0, 0? Definitely....

                                         

                                        Cheers!

                                         

                                        sd

                                        • 18. Re: White background causes colour shift
                                          jay fresno Level 1

                                           

                                          The question now remains is, is this just an optical illusion (meaning visible only on the screen) or is will it translate into print? Have you had any experiences with this?

                                          I printed your file to my Epson color printer; also printed it as color separations to my HP black and white printer. The color in the rectangles look even throughout -- there is no indication that the white rectangle has any effect on the final output, at least on these two devices. (Simulate Colored Paper was not turned on.)

                                          • 19. Re: White background causes colour shift
                                            JETalmage Level 6
                                            The question now remains is, is this just an optical illusion (meaning visible only on the screen) or is will it translate into print?

                                             

                                            That's a very easy thing for you to test yourself, Shunith. Just print seps to a PostScript laser printer or to Adobe PDF.

                                             

                                            If you do the latter, and then open the resulting PDF in AI, you'll find that the result is the same whether the screen display option is on or off. If you build the test file like mine, you'll also find that the C, M, Y, K filled rectangles are split into three paths each, where they overlap the white object below. Their grayscale values, however, will be the same.

                                             

                                            You'll further find that the black text adjacent to, but not intersecting with the "translucent" rectangles is present on all four seps, but is white on all but the black sep. On each sep, the other three sets of rectangles are present as well, also filled with white.

                                             

                                            In short, Illustrator does all kinds of "untidy" smoke-and-mirrors things when it creates PDFs and prints/exports files with transparency features (and when doing live effects like Compound Shapes). You choose to "trust" these convoluted constructs when you use such features as-is.

                                             

                                            I would not be at all surprised if someone on AI's development staff said that the display aberation noted in this thread is by design. As I said, I neither pretend to understand, nor would necessarily agree with, the "logic" for it.

                                             

                                            JET

                                            • 20. Re: White background causes colour shift
                                              shunithD Level 3

                                              jay fresno wrote:


                                              I printed your file to my Epson color printer; also printed it as color separations to my HP black and white printer. The color in the rectangles look even throughout -- there is no indication that the white rectangle has any effect on the final output, at least on these two devices. (Simulate Colored Paper was not turned on.)

                                              Thanks Jay...

                                               

                                              Will also check and revert... no access to a printer of any kind at the moment... thanks again

                                              • 21. Re: White background causes colour shift
                                                shunithD Level 3

                                                JETalmage wrote:

                                                That's a very easy thing for you to test yourself, Shunith. Just print seps to a PostScript laser printer or to Adobe PDF.

                                                Thanks for the reply JET... will check it out myself on the lines you suggested. Travelling at the moment so will revert on the tests after the end of this week...

                                                 

                                                Cheers...

                                                 

                                                Shunith

                                                • 22. Re: White background causes colour shift
                                                  Wade_Zimmerman Level 6

                                                  so one would goto View>Overprint Preview if one want to see how a fie will print on press.

                                                   

                                                  What you are seeing is art over another art one transparent and one opaque though it has not color and it is underneath the top object and the top object is not set to overprint  you are still seeing the art below, the question is should it being doing this?

                                                   

                                                  if you want to see how it prints you should view your document in Overprint Preview to see the colors more accurately.

                                                   

                                                  The problem is simply the wrong view option and nothing more.

                                                   

                                                  Hope this helps.

                                                   

                                                  Screen shot 2010-01-17 at 11.10.44 PM.png

                                                   

                                                  Screen shot 2010-01-17 at 11.11.03 PM.png

                                                  • 23. Re: White background causes colour shift
                                                    shunithD Level 3

                                                    Hi...

                                                     

                                                    Back... thanks for the answers... will check and revert...

                                                     

                                                    SD