8 Bit or 16 bit , sRGB or Pro Photo

Started Sep 11, 2019 | Discussions thread
pixelgenius Senior Member • Posts: 4,224
Re: The difference is ...

technoid wrote:

knickerhawk wrote:

pixelgenius wrote:

technoid wrote:

Ken60 wrote:

Sure , despite all this pixel , or dot , peeping .... I truly think the 16 bit workflow all the way to the printer allows the ability to keep the image on screen in photoshop and make little changes, aesthetic adjustments , and go right out to print without having to reduce the bit depth.

Another little note from this set of prints is the blue ball. If you peek at the first set of charts I posted, look at the top right blue ball. Specifically at the outer area of darker tones.... horrid in the 16 bit Pro Photo and quite clean in 8 bit sRGB ! So much for the dedicated blue cartridge of the Pro 1000.

Anyone care to say which black ball four posts or so back , is the 8 bit Pro and which the 16 bit Pro ?

Hi Ken,

Just got some time and loaded Gamut_test_file_flat.tif in PS. It's 16 bit, ProPhoto RGB. I deselected Edit-Color Settings->Use Dither.

I duplicated it then selected Windows->Arrange->Match All so the two tabs are in the same position. This makes it easy to switch back and forth from one image to another and see even the most subtle changes. Much better than side by side.

Then I converted the duplicate to 8 bit using: Image->Mode->8 Bits/channel. It's still in ProPhoto RGB of course.

Switching tabs back and forth from the 16 bit to 8 bit versions I see no difference at all. Not even subtle changes. Just nothing at all.

I'm seeing exactly what you report as well. I'm running a full, 10-bit video path, using a SpectraView. I looked at all balls and the gradients while at 100% in PS, they are visually identical FWIW.

At what scaling are you doing the comparison? Doesn't it seem odd to you that taking a synthetically generated gradient from 16 bit to 8 bit (without dithering either) is producing no visual difference at all?

The results were exactly what I expected.


I tried various scalings as well as 100%. Even 800%. Couldn't see any difference at all anywhere. I can, using the info window and setting the resolution at 32 bits which shows RGB values scaled from 0.000 to 1.000, see small differences on some pixels in the LSB. Not visible though.

Possible that a regular 8 bit display, especially using a video control card with LUTs for the RGB channels, that one could see an occasional, small difference due to the LUTs sometimes taking a double step between rgb steps. Should be unusual and hard to spot.

Indeed. But the two of us have no such limitations. 

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