8 Bit or 16 bit , sRGB or Pro Photo

Started Sep 11, 2019 | Discussions thread
knickerhawk Veteran Member • Posts: 7,007
Re: 8 Bit or 16 bit , sRGB or Pro Photo

Ken60 wrote:

Go into photoshop and go to colour settings..... look for "dither 8 bit" and uncheck it.

Close Photoshop and download the chart I linked. open it as a 16 bit Prophoto and call it 16 bit. Now convert it to 8 bit and save as 8 bit. With both open and select two windows side by side , zooming in on the black and white ball.

Now look at the two balls in 16 & 8 bit together each covering half your screen. What you will start to see is the real 8 bit , with all the horrid things that it can deliver, not the faked version of 8 bit you are claiming is as good as 16 bit ...... but dithered to fake it.

The dither on/off switch doesn't make that much of a difference here even with a purely synthetic image as is the case with the balls. The banding will just look a little more jagged. With a naturally dithered image, which is usually the case with photographs that aren't hugely edited, the dithering setting will be even less relevant.

More importantly, your experiment is failing to address a fundamental question: what is the bit-depth of your monitor? At most, your monitor is no more than 10-bits deep (and it may not even be working at a true 10-bit depth even if theoretically capable of doing so). Nevertheless, you're able to see even on an 8 bit monitor a difference between the original 16 bit image and the 8-bit truncated version of the image. The 16 bit version looks better (at least it does on my 8-bit iMac monitor). You can see this for yourself by looking at the screen captures in my post here. Those are screen grabs from my 8-bit monitor, yet the 16 bit ProPhoto strip clearly has less noticeable banding than the 8-bit ProPhoto strip.  Bottom line: viewing a 16 bit image on an 8 bit monitor is not the same thing as converting the 16 bit image to an 8 bit image and viewing the 8 bit image on an 8 bit monitor. Similarly, sending a 16 bit image to a printer through an 8 bit driver is not necessarily the same thing as converting the 16 bit image to an 8 bit image and sending that 8 bit image to a printer through an 8 bit driver.

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