How to Dither

[EchoingWhisper]

How do you dither 8 bit (4x8bit) photos in Photoshop?

 

[clanthar]

From the Photoshop File menu select Save for Web and Devices.

In the dialog that opens change JPEG to GIF and set the desired number of colors (bit depth).

Photoshop will dither the image.

Joe

 

[EchoingWhisper]

From the Photoshop File menu select Save for Web and Devices.

In the dialog that opens change JPEG to GIF and set the desired number of colors (bit depth).

Photoshop will dither the image.

Joe

No, I am trying to fix posterisation. The stock image I got required some editing and I were given an 8 bit file. Is there anyway I could fix or avoid this strong posterisation? I have the original 8 bit photo (I don't have the 16 bit photo).

 

[clanthar]

Oh dear, posterization = complete data loss. You have to replace the data with either cloned or manufactured data. To manufacture data try adding noise, using the Photoshop texture filters and blending in gradients -- this can often work better if you only add the noise, grain, texture to a single channel.

Tough problem.

Joe

 

[EchoingWhisper]

Is there any way I could darken the photo without posterization? I resorted to B&W which seems better because the band are less noticeable even though the posterization is actually stronger.

 

[EchoingWhisper]

Actually the stock image itself already have slight posterization.

 

[KmH]

This really isn't the forum section to post this in.

But, many 8-bit images have zero editing headroom, like the stock photo you paid for that already has banding.

I would bet the use license for the stock photo is an RF (Royalty-Free) license?

 

[analog.universe]

As others have said you're kind of backed up against a wall working with 8-bit.

The solution I've used (to varying success, depending on how bad the original is), is to first upscale the image (2 or 3x). Then I add some noise (totally a trial and error thing to see which type and how much looks like it will be most effective). I then use a blur of some kind (again, trial and error). Then scale the image back down, and mess with some sharpening. Breaking the image into layers based on which areas need the most help can be useful, since this is quite a destructive process, and will remove detail from areas that don't really need banding correction.

It really is polishing a turd, but... still better than not polishing it I suppose.

 

[EchoingWhisper]

This really isn't the forum section to post this in.

But, many 8-bit images have zero editing headroom, like the stock photo you paid for that already has banding.

I would bet the use license for the stock photo is an RF (Royalty-Free) license?

Yes it is.