Banding when using the (Radial) Gradient

[marc_schmidtmayer]

Hi,

 

When I use a Radial Gradient going for example from white to black, I can see

some banding on my screen. But it seems not to be real because when using the

eyedropper point sampler to obtain the RGB values, the progressively

increase/decrease.

 

I've found this topic about this 'problem' : http://www.photo.net/bboard/q-and-a-

fetch-msg.tcl?msg_id=00L4bY.

 

But after reading this, it is still not clear to me !

 

What is the problem ? The software, the monitor, the graphics card or the

calibration software ?

 

Anyone ?

 

I use Pantone Huey on 2 Samsung Syncmaster monitors : 215TW and 193P. On both

the banding occurs ...

 

Thanks, Marc.

[anthony_r]

You need to understand what banding is first and why it happens. Do a search on banding via

google or something. It may only be showing on your monitor. Only way to know for sure is

to print it.

[morrie_gasser]

I think it's a monitor artifact. I get banding with Photoshop gradients, too, on a large Dell

LCD display, but not on my Apple Cinema display or my CRT monitor. It's hard to imagine

how the calibration could cause banding. I suppose in theory it could be the graphics card

but that seems unlikely. Can you try saving the gradient file and viewing it in a different

program?

[marc_schmidtmayer]

I viewed it in another program, but the problem is the same.

 

 

Strange that there are so few answers ... I thought that many people would have the problem or is the problem limited to just a few monitors ?

[ted_marcus1]

It's a monitor artifact that is all too common. Adjusting it for photography by reducing the brightness from the excessive factory default and calibrating it can worsen it or make it visible.

 

CRTs are analog devices that can smoothly vary the intensity of the electron beam. But an LCD monitor can "twist" the liquid crystals to admit the backlight only in discrete steps. On all but the most expensive monitors intended for graphics professionals, there are only 256 steps per color (some only allow 128). Calibration works by adjusting a look-up table in the video card to alter some of the levels sufficient to produce a standard brightness curve for each color. That can produce (or increase) visible banding in gradients.

 

A gradient will reveal banding that might not be visible in real-world images. So it may not be a problem, or it might be so limited that you can live with it. If banding is excessive, or visible in images without computer-generated gradients, you may need a high-end monitor that uses 10-bit color rather than 8-bit.

[marc_schmidtmayer]

Thanks for the explanation and help.