20 Replies Latest reply on Jun 12, 2007 12:08 PM by Ramón G Castañeda

    Defringe

      XP, CS3, ACR 4.1, Canon 20D, 17 - 55 mm 2.8 IS

      The defringe control does not seem to be working. I have the classic example of fine tree branches against an almost blown sky. Unfortunately one can't place a precise point in the image (100%) to register color-value changes. Coming as close as possible, the blue value remains about the same. Some numbers:(original) 114,122,152; (after "defringe all edges") 116,122,147.
      On the top edge of the branch, showing no fringe, numbers are: 153,150,156.
      As expected, CA sliders have no positive effect.
      Fringe can be desaturated using HSL (blue & purple), but that affects the entire image and so, to mask, the process must be moved to PS. It would be nice to be able to use that edges mask from sharpening!
      Am I expecting too much, or is the defringe control not working? My result bears no resemblance to the Schewe example.
        • 1. Re: Defringe
          Level 1
          I'm interested in why no one has responded to my earlier message.
          • 2. Re: Defringe
            Ramón G Castañeda Level 4
            Paul,
            > why no one has responded to my earlier message.

            There can be many reasons for that. Don't take it personally.

            Some users may not be experiencing your problems. Others may not understand the question as posed. Etc.

            Remember that this is a user to user forum and no one has any obligation to respond to a given question.

            Personally, I am not a Windows user, so I skip most Windows related topics, and, besides, the Defringe function is working nicely on my setup on those few images where I've needed it.
            • 3. Re: Defringe
              Wolf Eilers Level 4
              In Jeff Schewe's excellent overview of ACR4.1 (on PhotoshopNews.com) he writes:

              >One of the long standing problems with many raw processing applications is how to handle near specular sensor flooding. This flooding seems to add either purple, red or magenta colors in the areas surrounding hot specular highlights.

              Does your image exhibit this "sensor flooding" effect that causes these unwanted colours?
              • 4. Re: Defringe
                Level 1
                Tossing out numbers really doesn't do much good. It would be far better to post examples with the various settings pllied.

                For example, you don't even mention which Defringe settings you've used...Highlight Edges won't really do what you are talking about since it was designed to remove fringing caused by sensor flood from specular highlights. The All Edges should do a better job...but you'll need to combine both CA settings (and your lens has a lot of CS) plus use of the All Edges.

                Even then, somethings simply can't be fixed...but examples would be more useful.
                • 5. Re: Defringe
                  Level 1
                  My apologies if it sounded like I had a right to a response, that wasn't my intent. It was merely interesting to me that a new feature that wasn't working for me garnered no interest.
                  My problem is fine edges against a nearly blown sky. The fringe is blue and purple. As I mentioned in my first post, this fringe is removable in LR using the HSL tool. I can also remove it with a half-dozen different methods in PS as well as with DxO. However, it would be nice if CR would do it "up front."
                  Unfortunately, after reading "help", I still don't know how to post images to this forum. If this is explained I'd be only to pleased to do so.
                  • 6. Re: Defringe
                    Ramón G Castañeda Level 4
                    Paul,

                    Upload your image to an FTP, like the one usually provided by your ISP, and include the link in your post.

                    You can also use Pixentral, which is free and requires no registration, for this purpose:

                    http://www.pixentral.com
                    • 7. Re: Defringe
                      Level 1
                      Thanks Ramon. Unfortunately my ISP doesn't provide an FTP site and the free site won't except .DNG files.
                      Jeff: if you have time away from your "debate" with DM on ACT, I'll send you a crop from the raw file and you can see if "defringe" works better in your hands. BTW, "CS?" Based on my attempts to use CA corrections in a number of other images, I don't believe the fringe I'm dealing with has any connection to CA (a lens condition). Those two controls make no visible improvement in the image. Allthough the arguments as to the source of this fringe continue, I can't believe it's anything but a sensor "nasty." It doesn't show up on film even when using inferior lenses. As I stated in my first post, I can eliminate the "colour" from the fringe using HSL controls. However, this also affects the colour in non-fringe areas, and hence is not desirable as a general method.
                      • 8. Re: Defringe
                        Level 1
                        > "The defringe control does not seem to be working".

                        I think this feature is "work in progress". It has lots of value, but sometimes I just wish there was an extra position (I don't know what!) in the menu!

                        - So far, in all cases where this feature has helped me, the best result has been the third item "All edges", not the middle position "Highlight edges". I accept that the third position may be a bit destructive of some other edges, but that appears to be a minor problem compared with the fringes that I am sometimes addressing.

                        - And sometimes I am still left with obvious purple fringes! I am left thinking "it worked with image X, why isn't it working with this image?"

                        I had been doing things in the order "sort out CA with the first 2 sliders, then select one of the items in the menu if there is still a problem". But if there still a problem after that, I can sometimes tweak it a bit by going back to the first 2 sliders, especially Blue/Yellow. They are probably not even addressing the same problem, but can still make a difference to the perceived image.
                        • 9. Re: Defringe
                          Ramón G Castañeda Level 4
                          Paul,

                          Try yousendit.com
                          • 10. Re: Defringe
                            Level 1
                            Yesterday, as the result of some testing, I discovered two interesting items.
                            1) "defringe" modestly affects my problem image when in an "unadjusted" state (i.e., as shot WB, all other adjustments set to "0"). Once the default "brightness" is applied, the effect seems to disappear. As I believe I stated before, CA fringe fixes have no salutary effect on this image because the problem isn't CA (see 2).
                            2) I bought a 30D last week so as to have 2 bodies. As the sky was a bright overcast yesterday, I took some shots of branches with the same lens and using the same settings. Imagine my surprise when I discovered the fringing was absent. Is it possible---I've never seen it mentioned in reviews---that Canon improved the sensor to reduce blooming?

                            I've had success "eliminating" the coloured fringe without affecting the remainder of the image using a modified "find edges" routine which I'll convert to an action. Nonetheless, I'd still like to see that capability in strengthened LR and/or ACR.
                            • 11. Re: Defringe
                              Level 1
                              Thanks Ramon, I'd forgotten I had an account there. Here's the address for the raw file.
                              http://download.yousendit.com/ED91A58001A2A2F8
                              • 12. Re: Defringe
                                Ramón G Castañeda Level 4
                                Paul,

                                I downloaded your dng file, and I have to say that I see a very substantial effect when setting Defringe to "All Edges" in ACR 4.1.

                                Try these settings in ACR 4.1:

                                White Balance: As Shot
                                Temperature: 5450
                                Tint: -4

                                Exposure: -0.65

                                Recovery: 0

                                Fill Light: 17

                                Brightness: +18

                                Defringe: All Edges

                                Leave all other settings untouched for this exercise.

                                You should be able to appreciate the very substantial effect of toggling Defringe between OFF and ALL EDGES, both at 100% and at 200%.
                                • 13. Re: Defringe
                                  Level 1
                                  I'm afraid I don't see what you see at 100 or 200%. I input the settings you specified and here's the value of a colour sampler placed at
                                  X= 1.135 Y= 4.252
                                  Defringe off: 91,96,134
                                  All Edges: 91,96,131

                                  I know it's a PITA, but you can check this by opening the defringe off version as a smart object in PS. Place a sampler at the co-ordinates I specify, then double-click the smart object symbol to return to CR. Change to "all edges" and then click open to return to PS. You'll now see the change in the sample point values in the info panel.

                                  If you find the time to do this, pls let me know the values you get.
                                  • 14. Re: Defringe
                                    Ramón G Castañeda Level 4
                                    Paul, <br /> <br /> I have no need to check numbers. The defringing is substantial and obvious to the naked eye at 100% and 200%. I have no explanation as to why you are not seeing it. <br /> <br /> Concentrate on the tip of bare branch shooting up vertically towards the 11 o'clock position from the same nearly-horizontal branch from which the broken fork leads straight into the water. Look at it at 100% and at 200%. <br /> <br /> Sorry, but that's all that I have time for. It's plain as day for me, and I need no stinkin' numbers. <br /> <br /> [EDIT to add image] <br /> <br />c <a href="http://www.pixentral.com/show.php?picture=17tR5HEIO7FTMZjIywaECVIdxKo37L" /></a> <img alt="Picture hosted by Pixentral" src="http://www.pixentral.com/hosted/17tR5HEIO7FTMZjIywaECVIdxKo37L_thumb.jpg" border="0" /> <br />c Click on the thumbnail
                                    • 15. Re: Defringe
                                      Ramón G Castañeda Level 4
                                      I edited the previous post to add a couple of screen shots. Click on the thumbnail.
                                      • 16. Re: Defringe
                                        Ramón G Castañeda Level 4
                                        Please note:

                                        * We're talking about a substantial defringing, not total defringing.

                                        * Your image is substantially overexposed.
                                        • 17. Re: Defringe
                                          Dirk Williams Level 1
                                          I downloaded the raw file also. I can see some change when defringing. It's very slight Is it me or is the image out of focus a bit. I can't get it sharp.
                                          • 18. Re: Defringe
                                            Ramón G Castañeda Level 4
                                            Dirk,

                                            Well, the 17-55mm is not Canon's sharpest or best lens. ;) The image responds well to further processing in Photoshop CS3 and PhotoKit Sharpener.
                                            • 19. Re: Defringe
                                              Level 1
                                              Dirk
                                              Re focus: you are correct in the area of the branches. I was experimenting with a new lens; the aperture was f2.8. The lower trunk is sharp, and it doesn't take much effort with the new ACR4.1 sharpening tools to tighten up much of the rest.

                                              The statement (not by you) that the image is overexposed is incorrect. A look at the histogram reveals that it fills the range without any clipping. The problem arises because the neutral sky next to many of the branches is 248 and a typical branch is ~76. These high-contrast edges seem to produce (with my 20D) a unacceptable fringe.

                                              I'm also noticing that the brightness control exacerbates the problem enormously.

                                              Thank you for your reply, it appears that it's not just my copy. As a result of this thread I have a much better appreciation of what defringe can, and cannot, do.
                                              • 20. Re: Defringe
                                                Ramón G Castañeda Level 4
                                                >The statement (not by you) that the image is overexposed is incorrect. A look at the histogram reveals that it fills the range without any clipping.

                                                The image is overexposed. No question about it.

                                                There are many branches or twigs that are totally invisible until you pull back the exposure by roughly two thirds of a stop.

                                                And the histogram does show clipping too, but I don't go by the histogram alone.