8 Bit or 16 bit , sRGB or Pro Photo

Started Sep 11, 2019 | Discussions thread
knickerhawk Veteran Member • Posts: 7,010
Re: The difference is ...

pixelgenius 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.

The problem truncating outlined below....

Ummmm...I responded to your post, not technoid's. YOU were the one who decided to truncate technoid's post when you responded half way into his post and then deleted the remainder of it.

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?

READ the sentence before asking questions that were outlined.

I just want to confirm that you only looked at the image at 100% and not scaled to any larger sizes. I wouldn't expect to see anything either at 100% (not for a steep gradient like these). At larger sizes, however, I'd expect the 8-bit banding to become increasingly visible (and it does on my antiquated 8-bit iMac). I believe that's what Ken60 is seeing too when he suggests examining the balls big enough to fill half the screen, but I don't know what system he's using.

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?

Not at all. Why don't you ask technoid the same question and you'll likely get the same answer. Wait, you don't have to because....

Of course, you didn't read this did you, but you decided to truncate it:

technoid wrote: So if you are seeing changes on your monitor from 16 bit to 8 bit mode something in your system setup is messed up.

As noted above, you were the one who did the truncating of technoid's post, so give yourself the stern scolding, not me.

I have two questions for you (and technoid as well if he's interested):

  1. Why should we conclude that something is "messed up" on a system that renders images with pure synthetic ramps encoded at 16 bits with less visible banding than the same pure synthetic ramp encoded at 8 bits? 
  2. Why have  you invested in your high end full 10-bit graphics/display solution if it doesn't result in any visible difference between the 8-bit encoded version and the 16-bit encoded version of the ramp? 
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