Skip to main content
W
WraithBand
Participant
November 17, 2019
Question

Gaussian blur banding question

  • November 17, 2019
  • 1 reply
  • 4710 views

Hello,

I have an issue when applying gaussian blur on my photos.

I'm working in 16 bits, that means when I export photos from lightroom to photoshop my export parameters are all in 16 bits under lightroom.

I checked that my image => mode is in 16 bits aswell under photoshop. I'm working in Prophoto RGB colour mode.

My screen is a BenQ SW2700 calibrated with a spyder pro 5. That means a 12 bit compatibility screen.

 

 

The problem is when I apply a Gaussian blur on Photoshop, even a small one (let's say 30 px) banding appears on my picture.

Is there something I didnt set up correctly ?

 

PS :

- My photoshop version is 21.0.0 and Lightroom is 8.4.1

- I'm working on W10

- My GC is a Geforce 1060 6Gb

This topic has been closed for replies.

1 reply

davescm
Community Expert
davescmCommunity Expert
Community Expert
November 17, 2019

Unless you have set up 30 bit display in Photoshop >Preferences >Performance >GPU Advanced and have a display chain that supports 30 bits all the way through  i.e. GPU card and driver (open GL), monitor and use of the correct ports  then you will be using 8 bits /channel for display. If any link in that chain is not capapble then you will only have 8 bits/channel.

 

Note : Lightroom uses dithering to hide banding even on 8 bit displays so do not assume that because you see no banding in Lightroom you are using more than 8 bits for display

 

Dave

W
WraithBandAuthor
Participant
November 17, 2019

Many thanks Dave for your explanations.

I think ports isnt a problem nor my monitor but maybe the GC.

Under NVIDIA control panel I can't change to 10bpc (it's greyed out to 8 bpc).

I 'll try to find out why.

 

Anyway I'm just surprised that a simple gaussian blur (even a small one) triggers so much banding !! I wanted to try adding a small orton effect to one of my photo and it's a total mess (banding). I'm just wondering if there isn't another issue on my Photoshop settup. That means one cannot apply a gaussian blur in 8 bit without banding...

 

 

D Fosse
Community Expert
D FosseCommunity Expert
Community Expert
November 17, 2019

What Dave is saying is that banding is in your display system, not in the data.

 

Photoshop works in 16 bit depth, but the display chain is 8 bit depth only, and that's where the banding happens - unless you have a 10-bit capable system.

 

And yes, Lightroom uses dithering. It does not support 10-bit display at all.

Terms & ConditionsAccessibility statement
Using the community Terms of use Privacy Cookie preferences Do not sell or share my personal information ad choicesAdChoices