Sorry but I'm not familiar with what banding means. I looked at your
gradient. It looks good but if it were a little wider it would be easier
to tell. The version I'm running is whatever is available on the
hosting server; the hosting company has it locked down so I cannot
run/check convert via a shell command.
For what it's worth, I made up a php script to create gradients. See
and compare results at:
www.dottedi.biz/tools/gradient_generator.php
What is being generated is/was not impeccably smooth. I'm viewing it on
a standard widescreen monitor at 1280x768 res. However, I changed the
monitor setting color quality from 16 to 32 bit and that makes a world
of difference. I'm not a hardware type - what would be the default
setting of most monitors coming from the factory?
The .gif version which I'm seeing now is 'fair' quality but the .jpg and
.png are much better.
-Bob
Ross Presser wrote:
I think I spoke too soon. While it's true that there is a 256 color
limitation to GIF and that puts an upper limit on the smoothness, your
result has definite banding. Like someone else who responded, I ran
your command myself today with IM 6.3.3 04/20/07 Q16 and got this
gradient:
http://rpresser.googlepages.com/gradient.gif
(yikes! Google says my site's bandwidth is exceeded. Oh well....
suffice to say that the gradient is smooth to the limits of
visibility.)
Anthony's answer about color quantization is more likely correct. What
version of IM are you using?
On 7/18/07, Bob Meetin <[EMAIL PROTECTED]> wrote:
Ross, That makes perfect sense. Here's a sort of related question. I
was messing around this afternoon. If I create a gradient from
white/black, white/red, they work fine, but if I do something extreme
like black/red, I end up with an almost rainbow-ish transition
sandwiched in between the black/red. Any idea? I can post to the group
list tomorrow. -Bob
Ross Presser wrote:
> GIF is limited to 256 colors (8 bits per pixel). You've specified a
> height of 600 rows. There is no way to get any smoother than what
> you've got.
>
> Try using PNG, or another 24 bits per pixel image format.
>
> On 7/17/07, Bob Meetin <[EMAIL PROTECTED]> wrote:
>> I'm using the following to create a gradient:
>>
>> convert -size 10x600 gradient:#000-#fff gradient.gif
>>
>> It creates the image fine, but the transition is not smooth See
>> sample at:
>>
>> http://dottedi.biz/codesamples/themes2/graphics/img.gif
>>
>> I used 100x600 in this sample to make it easier to visualize the
>> problem. What option do I use to make this a smoother transition
>> gradient?
>>
>> -Bob
>>
>> _______________________________________________
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>>
>
>
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