Gray Gamma 2.2 space and Photoshop2022 (23.1.1)
Hi List members Adobe RGB (1998) is gamma 2.2. So I was surprised to see that Photoshop (2022 23.1.1) changed the RGB values of a step-wedge I made in Gray Gamma 2.2 space after I converted it into Adobe RGB space. For example, in Gray Gamma 2.2 space my wedge starts out with RGB values, 0,0,0 / 5,5,5 / 10,10,10 / 15,15,15 / 20,20,20…. and the AdobeRGB(1998) conversion goes 0,0,0 / 13,13,13 / 18,18,18 / 22,22,22 / 27,27,27… Hmm… I just tried the same thing in Photoshop2019 and the RGB numbers stay the same for the conversion from GG2.2 to adobeRGB(1998) and back again. There are some other weird things happing with Photoshop 2022 handling of Gray Gamma 2.2 space black point. If I use a levels layer and lift the black point output level, I have to lift it to 5 before an eye dropper on my image on full black patch, finally moves from 0 to 1. That’s not right. REQUEST Can someone else on the list check this out. And let me know if you are seeing the same behaviour? Maybe there is something broken with our particular install? I am going to stop using Photoshop 2022 with my GrayGamma 2.2 space images till I can get to the bottom of this. Regards Peter Miles
I don't see a Photoshop problem here. With the gamma alone, why would you expect the values to remain the same? The lab values of the two (gray and Adobe RGB (1998) ) are the same when I view them before and after conversion (Lstar-0/4/5/710).
On Feb 12, 2022, at 7:31 PM, Peter Miles via colorsync-users <colorsync-users@lists.apple.com> wrote:
Hi List members
Adobe RGB (1998) is gamma 2.2. So I was surprised to see that Photoshop (2022 23.1.1) changed the RGB values of a step-wedge I made in Gray Gamma 2.2 space after I converted it into Adobe RGB space. For example, in Gray Gamma 2.2 space my wedge starts out with RGB values, 0,0,0 / 5,5,5 / 10,10,10 / 15,15,15 / 20,20,20…. and the AdobeRGB(1998) conversion goes 0,0,0 / 13,13,13 / 18,18,18 / 22,22,22 / 27,27,27…
Hi Andrew. Thanks for the reply. [regards RGB values staying the same when converting between Gray Gamma 2.2 <-> Adobe RGB (1998) ] <snip> With the gamma alone, why would you expect the values to remain the same? Two reasons. 1: RGB pixel values stay the same when doing conversions from Gray Gamma 2.2 <-> Adobe RGB (1998) in Photoshop 2019. 2: My understanding is that the Gray axis of Adobe RGB (1998) and the 'Gray axis' of Gamma 2.2 space are identical. Values 0 to 255 encoded Gamma 2.2. So the color meaning of RGB values along the gray axis of Adobe RGB (1998), and the color meaning for the same 'RGB' value in gray gamma 2.2 space are also identical. So that's a null conversion between them. And that expectation is being meet with the behavior of Photoshop 2019. It does not change the RGB values for gray, when converting in either direction between Adobe 1998 <-> Gray Gamma 2.2. But Photoshop 2022 does (on my install). Silent Changes of RGB values in PS 2022: This gets more interesting. I created a patches in PS 2019 in Gray Gamma 2.2 space. The RGB patch values were 0, 5, 10, 15, 20. I then saved it with Gray Gamma 2.2 embedded. I opened the very same file in PS 2022. The eye dropper in PS 2022 indicates that the RGB values have silently been changed (without any pop-up warnings) to 0,1,3, 6,12. Yet the L* meaning of those new numbers did not change. (all profile mis-match warnings are on.) Implied Gray Gamma 2.2 implementation Change in PS2022: The eyedropper is indicating that PS 2022 has silently changed the RGB values in my PS 2019 Gray Gamma 2.2 file. But the L* meaning of the pixels is being preserved. But two files having the same colour meaning, while using different RGB pixel values to achieve them mean that the two images are not encoded in the same colour space. If the RGB numbers in PS 2022 are to believed, that would mean that Gray Gamma 2.2 in PS 2019 is not the same as Gray Gamma 2.2 in PS 2022. Either that, or the eyedropper RGB Pixel read-out values in PS 2022 are just plain wrong. (For Gray Gamma 2.2 space.) Other PS 2022 odd behavior 2: Make a solid black canvas (0,0,0) in Gray Gamma 2.2 in PS 2022. 8 bit. Put a levels adjustment layer above it. Place an eye dropper and set it to display RGB values, to monitor changes made from the Levels layer. Slide the Levels output Black-Point slider up one step at a time to make the black image lighter. In PS 2022 I need to move the Levels output slider to '5' before the image even begins to indicate a change. And even then it only changes to RGB 1,1,1. In PS 2019 if I do the same thing and move the Levels output black-point slider up, The full black RGB values lift in lock-step to the Levels output slider value. At slider value 5, the image Black is lifted to '5,5,5'. But not in PS 2022. Other PS 2022 odd behavior 3: Make a new canvas, Gray Gamma 2.2 image in PS 2022. In 'Tools' pallet change the foreground pallet color. Type 15, 15, 15 into the RGB settings. Flood the canvas with this color. Place an eye dropper in the canvas and change the display to show RGB values. My eyedropper says the canvas is flooded with 14,14,14. Any one else getting this sort of behavior with Photoshop 2022? Thanks Peter Miles
On Feb 13, 2022, at 1:34 AM, Peter Miles via colorsync-users <colorsync-users@lists.apple.com> wrote:
Hi Andrew. Thanks for the reply.
I don't have your version of Photoshop 2019 archvied so I'll have to see what I can install on an old Mac. I did the conversion on my gray gamma squares in Lightroom Classic to Adobe RGB (1998) and get the same results as I got in Photoshop (2022) for both RGB triplets and Lab values. So those two (modern) versions are in sync. You may need to upload your gamma test file (Dropbox?) so others can see what's up there. What sampling do you have set for the info palette in Photoshop? Andrew Rodney http://www.digitaldog.net/
On Feb 13, 2022, at 2:34 AM, Peter Miles wrote: 1: RGB pixel values stay the same when doing conversions from Gray Gamma 2.2 <-> Adobe RGB (1998) in Photoshop 2019.
Not necessarily!! The RGB values in the Info palette and Color Picker are subject to your RGB Working Space and intent in Color Settings.
2: My understanding is that the Gray axis of Adobe RGB (1998) and the 'Gray axis' of Gamma 2.2 space are identical. Values 0 to 255 encoded Gamma 2.2. So the color meaning of RGB values along the gray axis of Adobe RGB (1998), and the color meaning for the same 'RGB' value in gray gamma 2.2 space are also identical.
Yes, but are you actually seeing AdobeRGB numbers in the Info palette and the ColorPIcker? I bet you’re not. Again, show us your Color Settings in both versions of Photoshop.
So that's a null conversion between them. And that expectation is being meet with the behavior of Photoshop 2019. It does not change the RGB values for gray, when converting in either direction between Adobe 1998 <-> Gray Gamma 2.2. But Photoshop 2022 does (on my install).
Maybe that’s because you have the defaults color settings with sRGB set as the RGB Working space… Also, what were your Color Setting when you mad the Grayscale file to begin with? I suspect you could have made the file with sRGB set as your working space so the 5,5,5 10,10,10 values were sRGB values - not AdobeRGB Gamma 2.2 values. Again, setting a grayscale file with RGB values is a funny thing to do and subject to this type of error.
Silent Changes of RGB values in PS 2022:
This gets more interesting. I created a patches in PS 2019 in Gray Gamma 2.2 space. The RGB patch values were 0, 5, 10, 15, 20. I then saved it with Gray Gamma 2.2 embedded. I opened the very same file in PS 2022. The eye dropper in PS 2022 indicates that the RGB values have silently been changed (without any pop-up warnings) to 0,1,3, 6,12. Yet the L* meaning of those new numbers did not change. (all profile mis-match warnings are on.)
Yup, because your RGB Working Spaces are different between the two apps…. It’s just calculating different values.
Any one else getting this sort of behavior with Photoshop 2022?
No they are both behaving identically for me when the Color Settings are synced. Please show us your Color Settings in both apps before we take this conversation further. Scott Martin www.on-sight.com Imaging Science for Art
Thanks Scott!! Yes, all our workstations “working color space” are normally set to AdobeRGB1998 and Gray Gamma 2.2 where I work. But on this workstation the “working color space” is often changed, depending on the group of files being worked on. And indeed, on this workstation PS 2022 is currently set to sRGB. That explains it. Yes, of course, the reported RGB eye dropper values are seen as a color conversion into a different colour space. From Grayscale space to RGB space. Phew !! …That such a relief. QUESTION. I always think of the “actual values” of greyscale files as being values from 0 to 255. Not a percentage, as the Photoshops eyedropper “actual values” report. That’s my photography background. In some situations, I want to know the actual 0-255 device values I'm sending in a grayscale file. Not just the device values 'reinterpreted' as a percentage. So how do you get photoshop to display the actual grayscale 0-255 values encoded in a grayscale file I have open. I can only use the RGB eyedropper display setting if I know in advance that my RGB “working colour space” uses the same gray-axis encoding as the grayscale file I have open? Or is there another way? Thanks so much for your Help guys!! Regards Peter Miles ________________________________ From: Scott Martin <scott@on-sight.com> Sent: Monday, 14 February 2022 6:09 am To: colorsync-users@lists.apple.com <colorsync-users@lists.apple.com> Cc: Peter Miles <P.Miles@massey.ac.nz> Subject: Re: Gray Gamma 2.2 space and Photoshop2022 (23.1.1) On Feb 13, 2022, at 2:34 AM, Peter Miles wrote: 1: RGB pixel values stay the same when doing conversions from Gray Gamma 2.2 <-> Adobe RGB (1998) in Photoshop 2019. Not necessarily!! The RGB values in the Info palette and Color Picker are subject to your RGB Working Space and intent in Color Settings. 2: My understanding is that the Gray axis of Adobe RGB (1998) and the 'Gray axis' of Gamma 2.2 space are identical. Values 0 to 255 encoded Gamma 2.2. So the color meaning of RGB values along the gray axis of Adobe RGB (1998), and the color meaning for the same 'RGB' value in gray gamma 2.2 space are also identical. Yes, but are you actually seeing AdobeRGB numbers in the Info palette and the ColorPIcker? I bet you’re not. Again, show us your Color Settings in both versions of Photoshop. So that's a null conversion between them. And that expectation is being meet with the behavior of Photoshop 2019. It does not change the RGB values for gray, when converting in either direction between Adobe 1998 <-> Gray Gamma 2.2. But Photoshop 2022 does (on my install). Maybe that’s because you have the defaults color settings with sRGB set as the RGB Working space… Also, what were your Color Setting when you mad the Grayscale file to begin with? I suspect you could have made the file with sRGB set as your working space so the 5,5,5 10,10,10 values were sRGB values - not AdobeRGB Gamma 2.2 values. Again, setting a grayscale file with RGB values is a funny thing to do and subject to this type of error. Silent Changes of RGB values in PS 2022: This gets more interesting. I created a patches in PS 2019 in Gray Gamma 2.2 space. The RGB patch values were 0, 5, 10, 15, 20. I then saved it with Gray Gamma 2.2 embedded. I opened the very same file in PS 2022. The eye dropper in PS 2022 indicates that the RGB values have silently been changed (without any pop-up warnings) to 0,1,3, 6,12. Yet the L* meaning of those new numbers did not change. (all profile mis-match warnings are on.) Yup, because your RGB Working Spaces are different between the two apps…. It’s just calculating different values. Any one else getting this sort of behavior with Photoshop 2022? No they are both behaving identically for me when the Color Settings are synced. Please show us your Color Settings in both apps before we take this conversation further. Scott Martin www.on-sight.com<https://apc01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.on-sight.com%2F&data=04%7C01%7CP.Miles%40massey.ac.nz%7Cd1c55b7a9b8441f9f3d808d9ef138b05%7C388728e1bbd0437898dcf8682e644300%7C1%7C0%7C637803689509736416%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=Mfbm11BkE3kqRN4jk7%2B6SD6Zte96DIOAiX14gYdfd9k%3D&reserved=0> Imaging Science for Art
On Feb 13, 2022, at 3:35 PM, Peter Miles via colorsync-users <colorsync-users@lists.apple.com> wrote:
QUESTION. I always think of the “actual values” of greyscale files as being values from 0 to 255. Not a percentage, as the Photoshops eyedropper “actual values” report. That’s my photography background.
In some situations, I want to know the actual 0-255 device values I'm sending in a grayscale file. Not just the device values 'reinterpreted' as a percentage. So how do you get photoshop to display the actual grayscale 0-255 values encoded in a grayscale file I have open. I can only use the RGB eyedropper display setting if I know in advance that my RGB “working colour space” uses the same gray-axis encoding as the grayscale file I have open? Or is there another way?
In Photoshop, you can view the RGB triplets as 0-255 scale (or high bit) and in Lightroom Classic it is 0-100 percent. I wish Adobe would provide both options in both products so we could always bounce back and forth, the don't. Gray again is yet another scale using 0-100%. And no, there is no 0-255 option/conversion. Maybe someone far more mathematically skilled (I'm not) can provide a simple calculation for each. My 'solution' is sticking with Lab which is an option in ACR/LR/PS. But again, I sure wish Adobe would simply allow us to toggle from each scale. Andrew Rodney http://www.digitaldog.net/
What???? The options are there in PS info panel, as long as you can multiply by 100. First make sure the Gray working space, the RGB working space and the image profile have the same gamma, such as gamma 2.2. This is because when the readout mode is not same as the image mode, the info panel uses the working space profile(s) to convert from image to the readout mode. Using the same gamma on all profiles assures that gray values convert to same RGB values. In the info panel: - For 0-255 readout of gray and RGB images, set the readout option to 8bit RGB. Gray 21 now read as 21,21,21. (The 8bit K readout is different, as 100% == black.) - For percentage readout of gray and RGB images, set the readout option to 32-bit. Multiply by 100% as 1.0 == 100%. This works for both K and RGB readouts. Lars, Adobe -----Original Message----- From: Andrew Rodney via colorsync-users <colorsync-users@lists.apple.com> Reply-To: "andrew@digitaldog.net" <andrew@digitaldog.net> Date: Sunday, February 13, 2022 at 12:49 PM To: "colorsync-users@lists.apple.com" <colorsync-users@lists.apple.com> Subject: Re: Gray Gamma 2.2 space and Photoshop2022 (23.1.1) On Feb 13, 2022, at 3:35 PM, Peter Miles via colorsync-users <colorsync-users@lists.apple.com> wrote:
QUESTION. I always think of the “actual values” of greyscale files as being values from 0 to 255. Not a percentage, as the Photoshops eyedropper “actual values” report. That’s my photography background.
In some situations, I want to know the actual 0-255 device values I'm sending in a grayscale file. Not just the device values 'reinterpreted' as a percentage. So how do you get photoshop to display the actual grayscale 0-255 values encoded in a grayscale file I have open. I can only use the RGB eyedropper display setting if I know in advance that my RGB “working colour space” uses the same gray-axis encoding as the grayscale file I have open? Or is there another way?
In Photoshop, you can view the RGB triplets as 0-255 scale (or high bit) and in Lightroom Classic it is 0-100 percent. I wish Adobe would provide both options in both products so we could always bounce back and forth, the don't. Gray again is yet another scale using 0-100%. And no, there is no 0-255 option/conversion. Maybe someone far more mathematically skilled (I'm not) can provide a simple calculation for each. My 'solution' is sticking with Lab which is an option in ACR/LR/PS. But again, I sure wish Adobe would simply allow us to toggle from each scale. Andrew Rodney https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.digitaldog.net%2F&data=04%7C01%7Cborg%40adobe.com%7C32d07ea564b7408d24b708d9ef430541%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C637803893407895913%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=ZSdtZ7JxTwYoovk%2FqquCf2soeAPeL%2B41M9IzfiD8RgM%3D&reserved=0 _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.apple.com%2Fmailman%2Foptions%2Fcolorsync-users%2Fborg%2540adobe.com&data=04%7C01%7Cborg%40adobe.com%7C32d07ea564b7408d24b708d9ef430541%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C637803893407895913%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=CsQx1MCYcVC7Fmv4nRv4efK%2Bx2yke%2BHMU2R%2FoznoCEQ%3D&reserved=0 This email sent to borg@adobe.com
On Feb 13, 2022, at 4:30 PM, Lars Borg <borg@adobe.com> wrote:
What???? The options are there in PS info panel, as long as you can multiply by 100.
Well again, it sure would be nice if Adobe would have its three photo products, Photoshop, Lightroom Classic and ACR provide the same numeric output options for info panel. Is this big enginnering? You'll also note, Photoshop and Lightroom Classic don't report Lab values the same. Photoshop truncates the values to 127/-128, LR doesn't and provides a bit more percision. Make G255/B0/R0 in ProPhoto RGB and examine the readouts in both. LR at least tells you via the numbers: "That's aint a color bud". <g>/ Some of Adobe's customers bounce back and forth between the three products all the time with the same image data, again, sure be nice of Adobe would at least allow us to view the data with all the same options. Without having to resort to any math. Andrew Rodney http://www.digitaldog.net/
Hi Lars Thanks for that reply. <snip> First make sure the Gray working space, the RGB working space and the image profile have the same gamma, such as gamma 2.2. This is because when the readout mode is not same as the image mode, the info panel uses the working space profile(s) to convert from image to the readout mode. Using the same gamma on all profiles assures that gray values convert to same RGB values. Thanks Lars. Thats a very clever solution. But I have to say that outside of a few photoshop users on this colorsync list, it's not a solution many photoshop users would think of to answer the question "what's the (0-255) value of the gray file I'm working on?". And even right now, with what I know, I am still wondering what RGB space has a gamma of Dot Gain 20%? For when I am tweaking the layered Dot Gain 20% Gray Space files I'm given. So I am wondering if you could advocate for Adobe to make the task of inspecting the 0-255 RGB values of grayscale images easier for us that are less technically inclined. Much Thanks Perer Miles ________________________________ From: Lars Borg via colorsync-users <colorsync-users@lists.apple.com> Sent: Monday, 14 February 2022 12:30 pm To: andrew@digitaldog.net <andrew@digitaldog.net>; colorsync-users@lists.apple.com <colorsync-users@lists.apple.com> Subject: Re: Gray Gamma 2.2 space and Photoshop2022 (23.1.1) What???? The options are there in PS info panel, as long as you can multiply by 100. First make sure the Gray working space, the RGB working space and the image profile have the same gamma, such as gamma 2.2. This is because when the readout mode is not same as the image mode, the info panel uses the working space profile(s) to convert from image to the readout mode. Using the same gamma on all profiles assures that gray values convert to same RGB values. In the info panel: - For 0-255 readout of gray and RGB images, set the readout option to 8bit RGB. Gray 21 now read as 21,21,21. (The 8bit K readout is different, as 100% == black.) - For percentage readout of gray and RGB images, set the readout option to 32-bit. Multiply by 100% as 1.0 == 100%. This works for both K and RGB readouts. Lars, Adobe -----Original Message----- From: Andrew Rodney via colorsync-users <colorsync-users@lists.apple.com> Reply-To: "andrew@digitaldog.net" <andrew@digitaldog.net> Date: Sunday, February 13, 2022 at 12:49 PM To: "colorsync-users@lists.apple.com" <colorsync-users@lists.apple.com> Subject: Re: Gray Gamma 2.2 space and Photoshop2022 (23.1.1) On Feb 13, 2022, at 3:35 PM, Peter Miles via colorsync-users <colorsync-users@lists.apple.com> wrote:
QUESTION. I always think of the “actual values” of greyscale files as being values from 0 to 255. Not a percentage, as the Photoshops eyedropper “actual values” report. That’s my photography background.
In some situations, I want to know the actual 0-255 device values I'm sending in a grayscale file. Not just the device values 'reinterpreted' as a percentage. So how do you get photoshop to display the actual grayscale 0-255 values encoded in a grayscale file I have open. I can only use the RGB eyedropper display setting if I know in advance that my RGB “working colour space” uses the same gray-axis encoding as the grayscale file I have open? Or is there another way?
In Photoshop, you can view the RGB triplets as 0-255 scale (or high bit) and in Lightroom Classic it is 0-100 percent. I wish Adobe would provide both options in both products so we could always bounce back and forth, the don't. Gray again is yet another scale using 0-100%. And no, there is no 0-255 option/conversion. Maybe someone far more mathematically skilled (I'm not) can provide a simple calculation for each. My 'solution' is sticking with Lab which is an option in ACR/LR/PS. But again, I sure wish Adobe would simply allow us to toggle from each scale. Andrew Rodney https://apc01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.digitaldog.net%2F&data=04%7C01%7Cp.miles%40massey.ac.nz%7C3bb328a5bc814cecc2a508d9ef48d543%7C388728e1bbd0437898dcf8682e644300%7C1%7C0%7C637803918384751525%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=NMP68woGVEVY5T6DaLcRkJyxmKyYI%2FZZFHL0UUm88Ek%3D&reserved=0 _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.apple.com%2Fmailman%2Foptions%2Fcolorsync-users%2Fborg%2540adobe.com&data=04%7C01%7Cp.miles%40massey.ac.nz%7C3bb328a5bc814cecc2a508d9ef48d543%7C388728e1bbd0437898dcf8682e644300%7C1%7C0%7C637803918384751525%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=VQDzjNoUuTw26srSARLALJFxU38N9q325k6C%2BVcJxFA%3D&reserved=0 This email sent to borg@adobe.com
<snip peter miles wrote> And even right now, with what I know, I am still wondering what RGB space has a gamma of Dot Gain 20%? For when I am tweaking the layered Dot Gain 20% Gray Space files I'm given. Sorry, I mis-remembered the color space of those odd gray color space files I sometimes get handed. They were in Generic Gray (not Dot gain 20%). Regards Peter ________________________________ From: Peter Miles via colorsync-users <colorsync-users@lists.apple.com> Hi Lars Thanks for that reply. <snip> First make sure the Gray working space, the RGB working space and the image profile have the same gamma, such as gamma 2.2. This is because when the readout mode is not same as the image mode, the info panel uses the working space profile(s) to convert from image to the readout mode. Using the same gamma on all profiles assures that gray values convert to same RGB values. Thanks Lars. Thats a very clever solution. But I have to say that outside of a few photoshop users on this colorsync list, it's not a solution many photoshop users would think of to answer the question "what's the (0-255) value of the gray file I'm working on?". And even right now, with what I know, I am still wondering what RGB space has a gamma of Dot Gain 20%? For when I am tweaking the layered Dot Gain 20% Gray Space files I'm given. So I am wondering if you could advocate for Adobe to make the task of inspecting the 0-255 RGB values of grayscale images easier for us that are less technically inclined. Much Thanks Peter Miles
<snip peter miles wrote> And even right now, with what I know, I am still wondering what RGB space has a gamma of Dot Gain 20%? For when I am tweaking the layered Dot Gain 20% Gray Space files I'm given. Sorry, I mis-remembered the color space of those odd gray color space files I sometimes get handed. They were in 'Generic Gray'. Regards Peter ________________________________ From: Peter Miles via colorsync-users <colorsync-users@lists.apple.com> Hi Lars Thanks for that reply. <snip> First make sure the Gray working space, the RGB working space and the image profile have the same gamma, such as gamma 2.2. This is because when the readout mode is not same as the image mode, the info panel uses the working space profile(s) to convert from image to the readout mode. Using the same gamma on all profiles assures that gray values convert to same RGB values. Thanks Lars. Thats a very clever solution. But I have to say that outside of a few photoshop users on this colorsync list, it's not a solution many photoshop users would think of to answer the question "what's the (0-255) value of the gray file I'm working on?". And even right now, with what I know, I am still wondering what RGB space has a gamma of Dot Gain 20%? For when I am tweaking the layered Dot Gain 20% Gray Space files I'm given. So I am wondering if you could advocate for Adobe to make the task of inspecting the 0-255 RGB values of grayscale images easier for us that are less technically inclined. Much Thanks Peter Miles
Hi Scott. <snip> Gray again is yet another scale using 0-100%. And no, there is no 0-255 option/conversion. But my understanding is that Grayscale pixel values are encoded using 0-255. Not 0-100%. If that's true, then surly no math would be required for photoshop to display the 0-255 values? If anything, I imagine math is needed to convert the 0-255 grayscale pixel values to their equivalent ink% values? And why doesn't photoshop eyedropper display the actual values for grayscale file (i.e. 0-255) when "Actual Color" is selected for the eyedropper? but instead, appears to display those values converted into 'ink % colospace' ? Or am I missing something again. Thanks again for your help! Peter Miles ________________________________ From: Andrew Rodney via colorsync-users <colorsync-users@lists.apple.com> Sent: Monday, 14 February 2022 11:48 am To: colorsync-users@lists.apple.com <colorsync-users@lists.apple.com> Subject: Re: Gray Gamma 2.2 space and Photoshop2022 (23.1.1) On Feb 13, 2022, at 3:35 PM, Peter Miles via colorsync-users <colorsync-users@lists.apple.com> wrote:
QUESTION. I always think of the “actual values” of greyscale files as being values from 0 to 255. Not a percentage, as the Photoshops eyedropper “actual values” report. That’s my photography background.
In some situations, I want to know the actual 0-255 device values I'm sending in a grayscale file. Not just the device values 'reinterpreted' as a percentage. So how do you get photoshop to display the actual grayscale 0-255 values encoded in a grayscale file I have open. I can only use the RGB eyedropper display setting if I know in advance that my RGB “working colour space” uses the same gray-axis encoding as the grayscale file I have open? Or is there another way?
In Photoshop, you can view the RGB triplets as 0-255 scale (or high bit) and in Lightroom Classic it is 0-100 percent. I wish Adobe would provide both options in both products so we could always bounce back and forth, the don't. Gray again is yet another scale using 0-100%. And no, there is no 0-255 option/conversion. Maybe someone far more mathematically skilled (I'm not) can provide a simple calculation for each. My 'solution' is sticking with Lab which is an option in ACR/LR/PS. But again, I sure wish Adobe would simply allow us to toggle from each scale. Andrew Rodney This email sent to p.miles@massey.ac.nz
Found an old copy of Photoshop CS (version 10) on a very old Mac. Converted my grayscale doc using your settings from Gray Gamma 2.2 to Adobe RGB (1998). Results are the same: 0/21/25/28/33. The same results I get in Photoshop CC 2022 and Lightroom Classic. Nothing wrong here, sorry. Andrew Rodney
Found an old copy of Photoshop CS (version 10) on a very old Mac.
I still have every copy of Photoshop on my Mac :-p https://www.on-sight.com/30-years-of-photoshop-and-counting/ <https://www.on-sight.com/30-years-of-photoshop-and-counting/> Sadly I didn’t keep the pre 1.0 versions….
Converted my grayscale doc using your settings from Gray Gamma 2.2 to Adobe RGB (1998). Results are the same: 0/21/25/28/33. The same results I get in Photoshop CC 2022 and Lightroom Classic. Nothing wrong here, sorry.
As I said that’s my finding as well. But that doesn’t help Peter, nor solve why he’s experiencing what he’s experiencing. I believe his confusion is common and relates to how Photoshop calculates color back and forth between these modes based on his Color Settings. I think he probably created the grayscale file with sRGB numbers and is then surprised when they change to AdobeRGB numbers… His new install is probably defaulting to sRGB as the working space... Scott Martin www.on-sight.com Imaging Science for Art
Peter, you didn’t tell us much about how your file was made but I think we can replicate what you’re seeing. In Photoshop 2022 goto the Color Settings and set the RGB Working Space to sRGB and the intent to RelCol. Create a new Grey Gamma 2.2 document and fill in a portion of the image with 5,5,5 and 10,10,10 etc as chosen in the Color Picker. [By the way it’s a bit weird to be choosing RGB values for a grayscale image]. Save this file. There’s no need to convert it - instead look at the info palette with one section set to RGB. It will show you the 5,5,5 and 10,10,10 values you’re expecting to see. Now goto the Color Settings and set the RGB Working Space to AdobeRGB. Take another look at the Info palette and you’ll see that the values are now 13,13,13 and 18,18,18. Now open this same file in any older version of Photoshop and repeat this test. You’ll find that it’s the same. Photoshop is consistent on this. sRGB and AdobeRGB don’t actually share the same 2.2 gamma curve. sRGB modifies the gamma 2.2 black approach with a linear segment, and that’s what we're seeing in this test. Goto https://en.wikipedia.org/wiki/Adobe_RGB_color_space <https://en.wikipedia.org/wiki/Adobe_RGB_color_space> and https://en.wikipedia.org/wiki/SRGB <https://en.wikipedia.org/wiki/SRGB> and search for “gamma” if you’d like to read up o this. The curious thing to me is why you’re seeing something different in PS2019. Check your Color Settings as there’s likely a discrepancy there. Cheers _____ As a side note I wish we could see Lab values to two decimals points. And I wish the Color Picker and Info palette were updated to clearly specify what color spaces and intents are being used. Scott Martin www.on-sight.com Imaging Science for Art
On Feb 12, 2022, at 8:31 PM, Peter Miles via colorsync-users <colorsync-users@lists.apple.com> wrote:
Hi List members
Adobe RGB (1998) is gamma 2.2. So I was surprised to see that Photoshop (2022 23.1.1) changed the RGB values of a step-wedge I made in Gray Gamma 2.2 space after I converted it into Adobe RGB space. For example, in Gray Gamma 2.2 space my wedge starts out with RGB values, 0,0,0 / 5,5,5 / 10,10,10 / 15,15,15 / 20,20,20…. and the AdobeRGB(1998) conversion goes 0,0,0 / 13,13,13 / 18,18,18 / 22,22,22 / 27,27,27…
Hmm…
I just tried the same thing in Photoshop2019 and the RGB numbers stay the same for the conversion from GG2.2 to adobeRGB(1998) and back again.
There are some other weird things happing with Photoshop 2022 handling of Gray Gamma 2.2 space black point.
If I use a levels layer and lift the black point output level, I have to lift it to 5 before an eye dropper on my image on full black patch, finally moves from 0 to 1. That’s not right.
REQUEST
Can someone else on the list check this out. And let me know if you are seeing the same behaviour?
Maybe there is something broken with our particular install?
I am going to stop using Photoshop 2022 with my GrayGamma 2.2 space images till I can get to the bottom of this.
Regards Peter Miles
_______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/scott%40on-sight.com
This email sent to scott@on-sight.com
participants (4)
-
Andrew Rodney
-
Lars Borg
-
Peter Miles
-
Scott Martin