August 2019 - colorsync-users

standard Lab values for C, M, Y, K for large format printer
by albert pedrosa 29 Aug '19

29 Aug '19

I tried measuring lab values of individual ink in large format printer and compared it with the standard per ink lab value for offset printing. The difference is significant. Will this affect the colorspace of the device? Regards

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Re: colorsync-users Digest, Vol 16, Issue 70
by Louis Dery 27 Aug '19

27 Aug '19

In photoshop, go to channel and select split channel Louis. Transmis via mon iPad > On 27 août 2019, at 15:00, colorsync-users-request(a)lists.apple.com wrote: > > Send colorsync-users mailing list submissions to > colorsync-users(a)lists.apple.com > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.apple.com/mailman/listinfo/colorsync-users > or, via email, send a message with subject or body 'help' to > colorsync-users-request(a)lists.apple.com > > You can reach the person managing the list at > colorsync-users-owner(a)lists.apple.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of colorsync-users digest..." > > > Today's Topics: > > 1. Splitting CMYK v4 profiles into 4 grayscale channel images > (forums(a)walkerblackwell.com) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 26 Aug 2019 15:13:36 -0400 > From: "forums(a)walkerblackwell.com" <forums(a)walkerblackwell.com> > To: ColorSync <colorsync-users(a)lists.apple.com> > Subject: Splitting CMYK v4 profiles into 4 grayscale channel images > Message-ID: <9D7BC4AD-70EA-4C43-BDEE-5BF483AAD489(a)walkerblackwell.com> > Content-Type: text/plain; charset=utf-8 > > Anyone here know the best way to convert an image to 4x grayscale CMYK channels/tiffs through a v4 cmyk (i1Profiler) profile? It?s been too long for me. > > This is for an experimental screen printing process BTW. > > Best, > Walker > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > colorsync-users mailing list > colorsync-users(a)lists.apple.com > https://lists.apple.com/mailman/listinfo/colorsync-users > > > ------------------------------ > > End of colorsync-users Digest, Vol 16, Issue 70 > ***********************************************

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Splitting CMYK v4 profiles into 4 grayscale channel images
by forums＠walkerblackwell.com 26 Aug '19

26 Aug '19

Anyone here know the best way to convert an image to 4x grayscale CMYK channels/tiffs through a v4 cmyk (i1Profiler) profile? It’s been too long for me. This is for an experimental screen printing process BTW. Best, Walker

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V2 profiles no longer show up in Adobe Photoshop and InDesign
by graxx＠videotron.ca 23 Aug '19

23 Aug '19

It appears to me that Adobe, in their infinite wisdom, now only honors V4 ICC profiles in their Color Settings > Working Profiles? I ran into this 'issue' using Adobe Photoshop 2019 20.0.6 and InDesign 2019 14.0.2 and Illustrator 2019 23.0.6 and Acrobat 2019 0.12.20036 on Windows 10. (Could be PC-related?) All my custom V2 profiles have stopped showing, all of a sudden. Whereas all my custom V4 profiles are still being listed. Best / Roger Breton

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RE: V2 profiles no longer show up in Adobe Photoshop and InDesign
by graxx＠videotron.ca 22 Aug '19

22 Aug '19

Darn... I knew the Mac was good for something 😊 / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com> On Behalf Of Andrew Rodney via colorsync-users Sent: Wednesday, August 21, 2019 7:50 PM To: 'colorsync-users?lists.apple.com' List <colorsync-users(a)lists.apple.com> Subject: Re: V2 profiles no longer show up in Adobe Photoshop and InDesign On Aug 21, 2019, at 5:44 PM, Roger Breton via colorsync-users <colorsync-users(a)lists.apple.com> wrote: > > It appears to me that Adobe, in their infinite wisdom, now only honors > V4 ICC profiles in their Color Settings > Working Profiles? Not that I can see. In fact, nearly all are in the folder installed (Recommended) are V2.1.0 And they all show up on this end..... Andrew Rodney http://www.digitaldog.net/ _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/graxx%40videotron.ca This email sent to graxx(a)videotron.ca

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Possible ColorSync discontinuity bug introduced in OS 10.14.6 with display "r/g/bTRC" tags?
by William Hollingworth 20 Aug '19

20 Aug '19

I'm starting to get reports of a severe banding problem that seems to be related to the recent macOS 10.14.6 update which includes some (unknown) changes to ColorSync. I've duplicated this and what I'm seeing is that when a display profile has the r/g/bTRC "curv" tag encoded as a "simple gamma" value rather than an array of points (typically 256), then there can be a big luminance discontinuity between level RGB=0 and RGB=1 - depending on the gamma value. I'm using a simple grayscale test image in the Preview app. The canned "Adobe RGB (1998)" profile encodes the 2.2 gamma as a "simple gamma" and this issue is evident when selected as a display profile. However the "Generic RGB Profile" encodes gamma 1.8 this way also but the discontinuity isn't very obvious. So higher gamma values make this more obvious. Re-encoding the profile's response curve as an array of points instead of a single "simple gamma" value seems to avoid the issue. However it was perfectly OK in previous macOS versions. Is anyone else experiencing this issue? It looks like X-Rite encode their TRCs as an array of points regardless, so probably most people won't see it. Anyone at Apple aware of this? Thanks Will Hollingworth

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Re: colorsync-users Digest, Vol 16, Issue 61
by David Miller 17 Aug '19

17 Aug '19

> >> On Aug 15, 2019, at 9:14 AM, David Miller via colorsync-users <colorsync-users(a)lists.apple.com> wrote: >> >> There?s definitely something wrong here in 10.14.6, and you don?t even need >> to use a display profile to see it. >> >> Set the display profile to Adobe RGB. It uses the TRC tags with the ?curv? type and >> simple gamma value. It also doesn?t have any calibration LUTs, which essentially >> turns off all LUT calibration and linearizes the contents of the video card. >> >> When you do this, use a 256 grayscale image with evenly spaced steps in Preview. > > Yes, I do see this in Apple Preview viewing a 21 step wedge TIFF using Adobe RGB (1998) as you advise. Safari and ColorSync Utility too. > I don't see it in Photoshop CC (latest version). I don't see it in Lightroom 8.4 in either Library or Develop modules. And this isn't limited to Adobe applications, GraphicConverter 9 matches Photoshop and Lightroom. > So yes, there's a bug but it's not affecting all applications equally. It does affect all Apple app's I've tried and it suggests Apple needs better beta testers like many who post here. > > Andrew Rodney > http://www.digitaldog.net/ > More info: 1. It’s not just Preview. Using QuickLook, for displaying images in a window directly from the Finder, without opening into any other application, also has the same problem. The fact that the wrong behavior exists at the base level of OSX functionality (both Quicklook as the “basest”, and Preview as the next level up) is a problem. And, Preview is color managed and the Finder (for QuickLook) is as well; both Preview and QuickLook honor display profiles when an image is opened and manually dragged between calibrated displays on the same system. 2a. The problem does not exist in OSX 10.14.2 (I have one partition I can still boot that way). So this is a new problem that wasn’t in the early releases of Mojave; it cropped up somewhere between 10.14.3 and 10.14.6. 2b. The problem does not exist in OSX 10.13.6 or earlier (also confirms that this is a new problem) David Miller Manager/Lead Developer, Consumer Graphics Datacolor

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Re: Possible ColorSync discontinuity bug introduced in OS
by David Miller 16 Aug '19

16 Aug '19

> Wiliam wrote: > > what I'm seeing is that when a display profile > has the r/g/bTRC "curv" tag encoded as a "simple gamma" value rather > than an array of points (typically 256), then there can be a big > luminance discontinuity between level RGB=0 and RGB=1 and >> Anyone at Apple aware of this? > > I*?ll ask around. > > >> After the update I cannot trust what I am seeing on my iMac 27? 5K. Color and contrast are washed out, > > Sounds like the profile and/or LUT associated with the display changed after the update, maybe reverted to the factory profile (the one created at login). Open System Prefs - Displays and reselect the profile you?d chosen before, even if it?s already selected in the list. If the display appearance changes, that?s what happened. (John Gnaegy: that’s not it; it’s not an issue with display profiles or LUTs changing or reverting - please see below) ******* There’s definitely something wrong here in 10.14.6, and you don’t even need to use a display profile to see it. Set the display profile to Adobe RGB. It uses the TRC tags with the “curv” type and simple gamma value. It also doesn’t have any calibration LUTs, which essentially turns off all LUT calibration and linearizes the contents of the video card. When you do this, use a 256 grayscale image with evenly spaced steps in Preview. What you’ll see is a large discontinuity between the first step (RGB 0,0,0) and everything that follows (much lighter). Here’s a very exact description of the problem. I have an image with 256 gray boxes, starting at 0,0,0 all the way to 255,255,255. On a properly functioning MacOS, with Adobe RGB set as the display profile, opening the image with Preview, and using Digital Color Meter to examine each box’s RGB value (set it to Native), each RGB patch measurement corresponds to the image’s digital value. In OSX 10.14.6, this is what I get instead: Box: RGB: 0 0,0,0 (correct) 1 14,14,14 (….wrong….should be 1,1,1) !!! 2 16,16,16 (……wrong…should be 2,2,2) !!! 3..89 Varying degrees of (wrong). Wrongness diminishes proportionately approaching box 90. 90..254 90,90,90 up through 255,255,255 (all correct) So there’s the problem. Starting with RGB 1,1,1 and up through 89,89,89, something is going wrong in 10.14.6 and pulling all of the shadows UP. The biggest discontinuity is going from box 0 to box 1, and the error gradually decreases per box step, until you eventually reach box 90, at which point everything is fine, the rest of the way. This is easily provable using the image and setup described above. (could also easily be proven in any image editing application for specific RGB gray values without even constructing an image) It looks to me as if there are other secondary effects from this issue; I’ll have to spend more time testing this. For instance, what we’re seeing this happening with is essentially the -uncalibrated state- of the display, with color management turned off (a side effect of using Adobe RGB as the display profile, with no calibration luts). If display calibration software, which puts native RGB values up on the screen with calibration disabled, instead gets colors that are artificially lighter in the shadows with the largest error being immediately above pure black), it’s going to compensate by using the calibration luts in the final display profile to pull down the shadows to compensate. This is what I think I’m seeing, after having run some preliminary tests. Assuming this “proves out”, it means that display calibration software can still, to a certain extent, make up for this problem by compensating in the eventual calibration luts that go into the profile. However, this is artificially compensating for the uncalibrated display response being “wrong”, and will result in the shadows being unnecessarily compressed. (And even then, I’m not seeing a completely smooth progression using a display profile; there’s still a “bump” going from box 0 to the boxes which follow). David Miller Manager/Lead Developer, Consumer Graphics Datacolor

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Problems with certain display profile types on MacOS
by Wire Moore 14 Aug '19

14 Aug '19

Is anyone on this list aware that MacOS has problems rendering in Preview / Quicklook and other built-ins (e.g., Photos) when using newer forms of ICC profiles? Described in this stackexchage post: https://apple.stackexchange.com/questions/271825/bug-macos-sierra-preview-q… The above post is quite open-ended in the problem description. To be more specific: I'm not an expert on this topic, but I can reproduce the problem easily using DisplayCal to make an XYZ LUT profile for my display on Mojave 10.14.6 and using Preview / Quicklook to display images. The rendering glitch is reliably a rolloff to black (clipping) in the bottom quarter tones. I've discussed with another user sees artifacts at top-end too depending on the display connection, i.e., HDMI as opposed DP / DVI. I am in conversation with Florian Höch, the author of DisplayCal over at the forums for his software, and he's investigated the problem and boils the situation down as follows: Höch Quote; //The only DisplayCal profile types compatible with Preview are the ones created by (DisplayCal) default, single curve (or gamma value) + matrix, with baked-in black point compensation, and calibration that maps input zero to output zero (so no black point hue correction possible)// I'm out of my league technically on the following point, but Höch goes on to say: //it’s just cLUT tags, and TRC tags that do not conform to the restrictions I mentioned above. Any A2Bx/B2Ax present, and the problem occurs. You can take any profile that Preview has problems with, remove the cLUT tags, replace the TRC tags, without changing anything else, and voila, Preview will be happy.// He observes that this is almost certainly a bug not an engineering limitation: //cLUT profiles work fine with ColorSync Utility by the way, which can be used instead of Preview to open images.// According to stackexchange post, this problem has been known since at least as early as Sierra. Höch added warnings to users in DisplayCal for any user running 10.8 or later because the problem is very common / repeatable. (Caveat I don't know if anyone can claim it's fully characterized) Adobe CC and other software also are known to work properly with profile configs that glitch on MacOS Preview / Quicklook. So to repeat, is there awareness here about this problem? Anyone here have any insights? What's the right way to engage Apple to get this fixed? I recently submitted "User Feedback" to Apple using their web portal. Ideally, MacOS will respect and render correctly using well-formed ICC profiles (! OMG we're talking Colorsync, people !). But if MacOS refused to accept an unsupported profile in Displays prefpane, it would be a fair compromise to silently barfing up wrong results so many users fall into a pit over MacOS behaving differently than their imaging applications. Thanks IA to anyone for taking the time to consider / respond. DisplayCal and Argyll CMS programs are awesome—And maybe disliked in some quarters because they are free and disruptive to a previously lucrative niche? I should shut my trap here... :) I am a messenger TIA /wire

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Hear from Facebook, Apple & L'Oréal @ #CIC27
by Roberta Morehouse 13 Aug '19

13 Aug '19

The Twenty-seventh Color and Imaging Conference (CIC27) keynote speaker's deep dive into color science and imaging with talks on perception-centered AR/VR displays, immersive experiences, and visibility. Register by 22 Sept. 2019 to save $100 off the full conference registration. Join us for a week of color in Paris 21-25 October 2019! Learn more at http://bit.ly/CIC27 * Dr. Marina Zannoli (Facebook Reality Labs) opens the conference with "Perception-Centered Development of Near-Eye Displays" a discussion on the use of the active observer environment to create compelling mixed reality experiences AR/VR displays in the future. * Dr. Andrew B. Watson (Apple) presents the Pyramid of Visibility, a simplified model of the spatio-temporal luminance contrast sensitivity function. During his talk, "The Chromatic Pyramid of Visibility", Dr. Watson describes efforts to develop an extension for the pyramid among other issues. * Panagiotis-Alexandros Bokaris (L'Oréal) presents "Let There Be Light: "An AR Immersive Experience" which focuses on the challenging aspects of video-projected #AR systems. Connect with us! LinkedIn IS&T CIC Group Twitter @ImagingOrg #CIC27

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