Known Participant

Question

Doesn't the Color Picker work in 16-bit mode?

Forum|Forum|7 years ago
December 8, 2018
7 replies
16792 views

When I switch Photoshop to 16-bit mode, the color picker seems to stay in 8-bit mode (the values only go up to 255 instead of 65535).

Doesn't the Color Picker work in 16-bit mode? Or is there some way to switch it to 16-bit mode, so you can see the actual color values?

kalamazandy

Known Participant

I wanted to add to this conversation because what I found seemed to be in line with the discussion here. I didn't know that photoshop wasn't actually 16bit, so that is annoying to me. I use photoshop for many tasks, and 3d maps is one of them. I had an idea on how to reduce banding when moving to 8 bit (sadly outside of photoshop because Adobe hasn't ever really had a good way to do that.) So I created a gradient fill with only a vew levels, to ensure I could clearly see banding. I settled on values from 48,48,48 to 52,52,52. So that gives me 5 pretty strong thick bands.

One thing that confuses me a bit is since the gradient fill is procedural, why I'm not getting a full value gradient in 16bit and 32bit. I'll explain:

In 32 bit mode I'm seeing 16 bit values of 1066 to 1107 over about 725 pixels (the width of one 8bit band). And it skips values also. It goes from 1074-1076 where there Should be a value between, no? And yeah, 32bit is assuming linear values rather than gamma corrected ones, which is why the values change. But I still thought that I should get all of the values between?

In 16 mode, the same area goes from 6503-6627. But now it's skipping values oddly: 6560,6562,6568,6571,6573. so +2,+4,+3,+2? what in the name of rounding kind of numbers are those!?

Can I see these number? No, Not important. I'm starting off with creating a gradient in 16bit so that it is smooth (or Should be) so that I can process the image in a different software that will convert the image to an 8bit format with dithering. And no, I'm not Just using a gradient created in photoshop, and I'm aware of the "dither" checkbox, however it is not good enough anyway. And it seems the only dither tools in color reduction within photoshop are moving to indexed color, which can't exceed 256 colors, so doesn't help you much if you are moving from 16million colors to 65,536 colors, which is a SUPER annoying standard. But I've found that converting from 16bit images to RGB565 ends up with much better quantize results than starting with "good enough" 8bit images. So the basic gradient here is just what I'm using to test out how photoshop treats the values. And it Seems that it's just rounding to what might seem "visually good enough?"

TheDigitalDog

Inspiring

"I wanted to add to this conversation because what I found seemed to be in line with the discussion here. I didn't know that photoshop wasn't actually 16bit, so that is annoying to me".

Actually, it's always been15 bits plus one level...done for algorithmic processing reasons. And since there really isn't a real-life source of full 16-bit images, that's all the precision Photoshop needs.

"And it Seems that it's just rounding to what might seem "visually good enough?"

Only if you accept that colors have to be seen and that lots of numbers are not colors, or are the same colors.

There are lots of RGB triplets that are different numbers that are the same color:

There are RGB triplets that are numbers that are not colors. R0/G255/B0 in ProPhoto RGB isn't a color. It is a device value:

http://digitaldog.net/files/ColorNumbersColorGamut.pdf

You're also kind of confusing colors with color numbers (device values) solely based on encoding.

As correctly outlined, if you see banding in a high bit image, its banding due to the display path, not the data. You can test this easily with this kind of image document viewed properly (at 100%) zoom:

https://www.dropbox.com/s/s14f4w7dq85r7oo/10-bit-test-ramp.zip?dl=0

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

Z

ZBalling

Inspiring

OK, fair enough 🙂

"Are you confused between a comma, a hyphen, and an asterisk? "

Floating point is a comma in my country. The fact remains Pantone cares about 2° or 10° observer and D50 vs D65 viewing illuminant. With quite a lot of numbers after decimal point.

Z

ZBalling

Inspiring

That is funny. Gimp does support 16 bit (0-65535) color picker and your app does not... Really!!!

c.pfaffenbichler

Community Expert

and your app does not...

This is a user Forum, so you are not really addressing Adobe here, even though some Adobe employees thankfully have been dropping by.

Z

ZBalling

Inspiring

Just look into this one repo GitHub - jursonovicst/gradient: 10-BIT DISPLAY TEST SEQUENCE

These are test files for 10 bit displays... I could not check colors with Photoshop 2018 and I had to use gimp. That is not normal. Besides that, don't you think that if Photoshop cannot pick up 16 bit color, than you should write 15 bit (0-32768), not 16 bit (0-32768), right? Or it should use 0,5 to really have 16 bit color. So this is a mistake in Adobe code. A MISTAKE. It will not be a problem for performance. Nvidia geforce 2080 can work 48 (or 48 + 16 alpha) bits without any problems. So does Snapdragon 855 or amd chips...

Chuck Uebele

Community Expert

As far as PS processing each layer separately, that is true, but it doesn't refuse the values to 8 bit, if you're working in 16 bit. PS has a hierarchy as to how it applies corrections, as I found out when I was having some issues with a process that I thought could be easily fixed. I was told that it wouldn't be easy as another process was implemented first, making the process I wanted corrected defendant on it, which was causing the issue. Again, this dealt with the very basic core of PS, which is difficult to change.

davescm

Community Expert

I wonder if we will see some changes in this area. Clearly Adobe are now working on the core compositing engine - hence the need to check "Use Legacy Compositing" to get round one or two of the early bugs it introduced.
Unfortunately apart from general comments that the engine is being updated , I've not seen any real detail on what that update entails.

True 16 bit would seem like a great opportunity now, as would 16 bit compositing (or even 15+1) at zoom levels less than 66.7%.

Dave

rob day

Community Expert

True 16 bit would seem like a great opportunity now

What output device is capable of outputting full 16-bits?

No digital halftone screen can output more than 256 gray levels because it would take a massive amount of printer resolution to modulate the halftone dots to more gray levels, so that eliminates most commercial print.

Stochastic screening typically used with inkjet printing would have a similar problem where both the horizontal and vertical printer res would have to be high enough to increment the dot spacing to 65K levels. You might argue that splitting the cyan, magenta, and black channels into light and dark value inks can gain some gray levels, but it's still nothing close to 15- or 16-bit.

Chuck Uebele

Community Expert

I seem to recall an Adobe engineer explaining that things like the color picker and input and output values on curves are only in 8 bit values, as the user can't perceive 16 bit values, and it just complicating the PS code. As mentioned above, 16 bit is to give extra range when making corrections to avoid banding and such artifacts.

BTW, Dag, I too have scored a perfect score on that test, several times.

D Fosse

Community Expert

https://forums.adobe.com/people/Chuck+Uebele wrote
I seem to recall an Adobe engineer explaining that things like the color picker and input and output values on curves are only in 8 bit values, as the user can't perceive 16 bit values, and it just complicating the PS code.

From a user perspective, I totally agree with that. Can you imagine typing 27356 into the Curves input field, and correcting 27405 to match? It's insane, considering that you probably can't see the difference between 249 and 250 unless you measure them.

rob day

Community Expert

From a user perspective, I totally agree with that. Can you imagine typing 27356 into the Curves input field, and correcting 27405 to match? It's insane, considering that you probably can't see the difference between 249 and 250 unless you measure them.

I think one frustration with the Color Picker is that while the RGB fields are 8-bit values, the C,M,Y,K,—S,B, & L are not. So if you are trying to spec a CMYK color in .5 percentages (or get its RGB equivalent) it gets difficult. A typical halftone screen can't be more than 8-bit, but it could define more than 100 gray levels and you might detect that difference in a highlight color.

If I try to enter something other than an integer in a CMYK field I get this warning

My 10.4% gets reset to 10, but the other space conversions change, so obviously the color changed even though I'm still seeing 10%C.

It would be better (at least for offset print work) if the CMYK percentage rounding wasn't to the nearest integer but to the nearest number.

InDesign does conversion rounding to 100ths

D Fosse

Community Expert

I have a feeling this is intentional. I can't think of any situation where you would need to input exact 16 bit values. And input is what the color picker is for.

For readout, use the Info panel as c.p. showed.

c.pfaffenbichler

Community Expert

Ah, I do apologize, the OP had asked about the Color Picker specifically but I guess I had misinterpreted

so you can see the actual color values

and assumed they wanted the readouts.

My mistake.

c.pfaffenbichler

Community Expert

And keep in mind that Photoshop 16-bit amounts to 15-bit + 1.

L

Lee JamesAuthor

Known Participant

Thanks for the answers.

I was aware you could do it in the info panel, but I just find it confusing why the Color Picker doesn't show the true values? I mean why not? Seeing 8-bit values kind of makes me question whether I'm truly in 16-bit mode and if everything is working properly.

I often use to Color Picker to do two things at once:

1. See the color of the pixel I've picked

2. Compare the colors of different pixels and see if they're actually different.

Not having 16-bit values makes this tool kind of imprecise and clumsy - though it's not a big deal.

Also, could anyone explain what is meant by "15 bit +1" ? I don't get that.

D Fosse

Community Expert

Suicide wrote
I often use to Color Picker to do two things at once:
1. See the color of the pixel I've picked
2. Compare the colors of different pixels and see if they're actually different.

16 bit depth isn't for appearance. It's for data integrity through repeated editing operations.

Visually separating 8-bit values is difficult enough, and in many cases you can't. Don't forget that 8 bit depth is all you get out of your monitor (at best 10 bit if you have a display system capable of that).

Try this one to give you a little perspective:

Free Online Color Challenge and Hue Test; X-Rite

I managed a perfect score on my second try, a fact I take some pride in because only a few % manage that. The first attempt gave two errors.

c.pfaffenbichler

Community Expert

Click on the eyedropper icon in the Info Panel and set it to 16-bit.

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