"Banding" in PS CS5.1

ed_o_brain

ed_o_brain

Suspended / Banned
Messages
711
Name
Daniel
Edit My Images
No
When I'm blurring or even using the brush tool on images I've taken in CS5.1 I'm getting some banding - particular in areas of the image which are fairly close in colour/tone. It looks a bit like posterisation, except it isn't.

A quick google has suggested a few things, like it can be caused by editing with 8-bit images, conversion between colour spaces etc.

I'm shooting with Nikon D300s/D700. I am capturing in 14-bit RAW with lossless compression switched on using the sRGB colour space.

I am then importing into LightRoom 3.41 where I do the RAW conversion. I then edit as a TIFF using the ProPhoto RGB colourspace at 16 bits/component.

I was using 12-bit RAW and 8 bits/component when I first noticed the problem.

I have tried adding noise before blurring and also converting to the LAB colour space but that's made no noticable difference. I have also tried 14-bit uncompressed RAW.

Will continue working through the variations, but would really appreciate some useful direction on this. Thanks.
 
I would appreciate an answer to this too...it's very evident in some black and white film scans I've done
 
Is it still there when you make a print, sometimes you can see it on screen but it magically disappears when printed.

Joan
 
I dare say they won't show on my printer when I print them - but I think that's because my printer doesn't have the colour depth my display does.

My understanding is that they shouldn't be there and there's something that's not right in my workflow for them to occur.

Further more, I didn't experience this when I was using Photoshop Elements to process my images. Switching to Lightroom, aside from this, has been brilliant and I really don't want to have to revert back to a slow and cumbersome way of doing things because of this banding.

I shall spend a bit more time later today trying various things to see if I can resolve it.
 
Clutching at straws here, but is it a screen redraw issue that comes and goes depending what scale you're viewing at? Is it evident when viewing at 100%?
 
Does it happen if you edit in PS without going through LR?
 
ed_o_brain said:
The banding is present when zoomed in on anything from 25% upwards.

I've tried changing the camera preset from sRGB to Adobe and also editing directly in Photoshop.

Starting to run out of ideas now.
Click to expand...

Anything? Every shot you process shows this problem? I've seen banding on shots that are say at high ISO or that have been forced from underexposure, processing in CMYK can do it...but it's pretty rare.

Can you post say three images (with exif) shot in different conditions that show the problem?
 
D700 Images

## dc17574
ISO 200 75mm f11 1/50 14-bit RAW lossless compression AdobeRGB
D700

RAW conversion with Adobe Camera Standard v2

Original
_DC17574.jpg


Blurred
_DC17574_blur.jpg


100% Crop
_DC17574_100pc_crop.jpg
 
Last edited:
Can anyone shed any light on this? Can people with high quality displays see it? ...Look at the centre/bottom of the green area of the last image where the green is darkest and then look slowly up.. I can see the bands (the look a bit like posterisation) as you work slowly up to the brighter green at the top of the image.

Any help would be much appreciated.
The problem is apparent too with View NX conversions from my D300s. I'm thinking it might just be my display...
 
Have to say I can't see any banding (Dell U2410 here)
 
Are you blurring the photos?

Seems to me that is what is causing the problem...as I don't see banding in any of my shots until I start messin' with the pxels.......

It is more than likely the backlighting of your monitor that causes the banding.

put the last image in the middle of your browser then scroll it up and down quickly and you will notice the banding move/change........

In other words don't pixel peep as you will forever, be over critical of everything.
 
Have you tried adding a little bit of noise after, does the banding still show then?
 
Yes, make a print, if it isn't on the print you are good to go.

Joan
 
I tried to replicate this and got exactly the same result, but having given it some thought I think it is inevitable.

Here’s my logic (if you can call it that)

First, here’s my take on the make-up of the colour images.

Each 8-bit RGB image is made up of three channels. The Red, Green and Blue channels.

Each channel is made up of an 8-bit grey scale component.
The maximum number of values you can squeeze into 8 data bits is 256, that is 0 to 255

So there are 3 channels, each with 256 possible values, so the product of these 3 channels (256 X 256 X 256 ) is 16,777,217 possible colour values. The 16 million colours regularly referred to.

As an example I tried a background green of 90, 140, 50 RGB values and put a circle filled with green made up of RGB 80, 130, 40 on it.
These are similar but clearly different colours, but numerically significantly apart:

Background 90 X 140 X 50 = 630,000
Foreground 80 X 130 X 40 = 416,000
Difference 214,000

This means that in this image there are a possible 214,000 colours between the background and foreground colours.

When you try to blur over for example 40 pixels, you are trying to fit 214,000 colours into those 40 pixels.

I don’t know exactly how Photoshop does the sums, but to my mind there are going to be steps of at least 214,000 / 40 = 5350 colour values, which in turn means each step is going to change each of the RGB values in the transition by approx. 17 (cube root of 5350)

No doubt the boffins at Adobe use some hard sums and tricky logs to improve this but it remains visible.

So, when I blurred my green on green, banding became visible to me at around 10 pixels of gausian blur, and got worse at 30ish pixels but I couldn’t resolve it on my monitor at around 250 pixels.
Don’t forget, this is with similar colours. It may be less evident with contrasting hues.

Try it.

I hope this makes sense. I may be wrong (and I know someone on here will put me right if I am) but it makes sense to me and the doctor says I’m not mad anymore. :bonk:
 
Last edited:
Interesting problem. I can definitely see the banding. The maths of the blurring filter shouldn't really be causing this (though I could be wrong!), have you tried saving it from Photoshop with the highest quality jpeg settings or a lossless format?
 
update - I've just updated my video drivers and the problem (if you'd call it a problem) is definitely less obvious.
 
It could be my display... have to admit all the monitors I have aren't of tremendous quality. That's the next thing on the shopping list, with nearly everything else sorted out.

Okay, these images have all been, as far as I can tell, upsampled from 14 bit .NEF files and saved as 16 bit .tiff files. The problems I can see in the JPEGs posted upthread are just as apparent in the tiff files.

I have also tried viewNX to do the RAW conversion and found the banding was still there once I'd edited in photoshop, just less apparent.

The gaussian blur shows the problem up really quite well. But other tools (even just the brush tool) used in Photoshop are having the same effect. If it were an issue with my display, I'm sure it would be apparent with some subtle gradients before they are blurred, and I've never noticed this before.

That said, for now I think my final conclusion is that there probably is an underlying problem that is most likely exacerbated by my display. I will experiment with some noise!

Thanks all for the feedback.
 
Have you actually ever printed anything from the files that show you the banding on screen? It just seems to me a bit of a waste of time trying to fix something on screen that maybe doesn't show up on a print....just my opinion

Joan
 
Give Dean aka the23rdman a pm, he was having some 'banding' issues too not long ago....I don't know if he sorted it but he will probably help/hinder (lol) your progress.
 
You must log in or register to reply here.
Back
Top