Please help? Banding issues in Mavericks after callibration

[HeidiLouw]

Hi there everyone, I am still very new to this forum and hope I can explain my problem correctly without being tooo long-winded. I was referred here by a local print press in Cape Town, and that I would get the right kind of help here rather than in one of my retouching forums
I upgraded my operating system to Mavericks and I had the screen calibrated by a professional with a quato calibrator shortly after. But now I am having banding issues with images and hoping someone can help me understand what is causing it?

I work with an iMac and in Photoshop CS6.
The specs of my machine
Processor: 3,1GHz Intel core i5
Memory: 16GB 1333 MHz DDR3
Graphics: AMD Radeon HD 6970M 1024 MB
Software Mavericks
243,67GB free of 1TB of hard disk space

I regularly move files off my computer after I have completed a particular job and don't keep them on my machine for long to preserve all the memory available I need to run CS and be able to work efficiently onmy images. I was working on Lion OSX before and did not have these issues banding? ...

I process images in 16bit and then convert to 8bit, as the files are smaller and more manageable.
The banding seems worse in 16bit, but is still visible in 8bit - pls see the examples I have provided.
I have tried different colour profiles(the generic i Mac setting and the newly calibrated quaoto setting), but the same happens and there is no change.
It is especially bad when I use the brush or clone stamp tools in Photoshop.
I work on a 100% opacity and between 7-30% flow depending on the tool used and the end result I require.
You can see clearly in the attached examples, that those edges are not graduated as they are supposed to react.. it must be a soft graduation from center to the edge with no hard lines or 'banding' as harshly as shown.

When the gentleman from digital distributors helped me calibrate my screen, he was struggling to set the gamut(?) on my screen and it would not set at 2 or even 2.2. My my shadows/blacks also seem slightly milkier than before. is this a calibration issue or an issue with Mavericks?

It makes my workflow very difficult and I cannot determine whether the banding is from my colour grades, or from the machine settings...does anyone have any idea how I can solve this issue without having to downgrade back to Lion, or is this my only option?

There are some screen grabs of what I see on my screen (but if i did not manage to attach them to this post, you can go to this dropbox lik https://www.dropbox.com/sh/081c3fygrv1kg6c/39e3rr8v1y )

I'd really appreciate someone help with this. Thanks so much

 

[Stephen Marsh]

Computer generated gradients are very unforgiving, even when created with lsb dither. Evaluate them at 100% magnification, if they are created in synthetic RGB working space, they will be converted to the monitor profile, which can cause display banding. Try creating the computer generated gradients directly in the monitor profile space so that there is no conversion and evaluate.

One could also try using the native gamma, rather than trying to force it to a standard (if this is causing banding). Photoshop and other colour managed programs will convert to the monitor profile, so it does not matter if the gamma is not standard. This will matter for web viewing, however you could have two settings, one for print work and the other for internet.

Try swapping the custom monitor profile for a generic sRGB profile to see if the profile is not good. Is the banding still there, does it change position, or are things now smooth?

Due to the cost of professional services for monitor profiling and the regular requirements for reprofiling, owning the hardware soon becomes cheaper than hiring somebody else to do the job.


Stephen Marsh

 

[HeidiLouw]

Thanks Stephen - will look into it right away.

 

[HeidiLouw]

I changed my profile to the Generic RGB profile in my display settings.
Went back to Photoshop and did the same as I have done on the file, the banding is definitely much less and still visible, but not as bad and defined as before.
Does this mean this is a calibration issue and the monitor must be re-calibrated?

 

[Stephen Marsh]

I changed my profile to the Generic RGB profile in my display settings.
Went back to Photoshop and did the same as I have done on the file, the banding is definitely much less and still visible, but not as bad and defined as before.
Does this mean this is a calibration issue and the monitor must be re-calibrated?

Sounds like this could possibly be the case. Perhaps also try the Display settings calibrate button to create a manual “eyeball” profile to see how this fares in showing banding.

Even under the best of conditions, monitors may require recalibration and reprofiling daily/weekly/monthly etc.

Remember, computer generated linear gradients are “perfect” any transform/edit has the great possibility to create banding, even when using the dither option in the gradient tool (cg radial gradients are even worse). The banding on a cg gradient may not show on output with a photographic image.

A great monitor torture test:

LCD monitor test images


Stephen Marsh

 

[maas]

Although it will not solve your problem its important to understand what banding is, Colours made of (or ripped at) 8 bits per channel have a max. of 256 steps / tints / colour values per channel available. This is because 2 raised to the 8th power = 256. 2 because each bit can be on or off, raised to 8th because you are probably using (or ripping at) 8 bits per channel. (1 byte = 8 bits and this is rooted in early computer geekdom). Spreading these 256 steps over a large physical distance results in visible banding. There are millions of colours available in 24 bit colour (256 R values x 256 G values x 256 B values) or 32 bit colour (256 c x 256 m x 256 y x 256 k) but no channel can have more than 256 individual levels / tints / steps. The 256 steps are used to create the entire range of the gradient, so a gradient from 0% to 100% over 100 inches will show more banding than a gradient from 0% to 10% over the same distance simply because the changes are less abrupt (roughly .4% in the first case, and .04% in the second). Each still has 256, and only 256 steps per channel available to it. So the distance covered and the amount of change from start to finish are the primary factors, other aspects of an image that can play part in showing banding is the angle of the pattern, rotate the entire image by 1 degree and see if the banding is visibly reduced

(credit where credit is due, the explanation on banding was courtesy of another forum member)

 

[Shawn]

I believe the older model Quatos were an XRite DTP94. I know that my DTP94 started to have trouble with some of the newer LED backlit wider gamut monitors a while back and had to be replaced with an i1 Display Pro -- which is what the newer Quato pucks appear to be. Based on your description of your iMac I'd say that you've got an LED backlit screen so depending on which version of the Quato he used it could be an issue with the calibration.

 

[rich apollo]

I had the same thought that Stephen did - go with the native gamma.

I suppose it's possible that Apple is using a less than optimum video driver, but it seems unlikely, especially considering that they built the machine.

Were you using the same guy to provide the same services before you upgraded? And we're all assuming that he was using the iColor software for the calibration.

 

[mastegman]

I had the same thought that Stephen did - go with the native gamma.

I suppose it's possible that Apple is using a less than optimum video driver, but it seems unlikely, especially considering that they built the machine.

It is my experience that the Apple monitors are less than ideal in this respect. The banding effect was most obvious when the 'Flurry' screen saver was available. Strangely, it has been eliminated from the latest version of the OS ;-). I am using a 1Tb fusion drive Mac Mini with 16gb RAM (Max) and an Eizo display. I could always use more RAM but the SSD makes up for a lot of that. The display takes care of the graphics. No problem.

 

[fordw]

Did you get your issue solved? I'm curious what it was as I also just moved to Maverick's and while no graphics issues yet, I have noticed a huge slow down even though I've increased RAM and there were no issues before.