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Gradient Banding


nisus
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Hi WDA,

 

Only in CS :confused: , 7.0 only does it under cymk & 16 bit I believe

I don't really understand what you mean...

 

I have this problem also with NONE-compressed images!

As soon as I draw a gradient in PS CS (especially blue...)

 

rgds

 

nisus

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Nisus,

 

Just used the compression to accent the banding- make sure it showed up (web).

 

I tried to get it to happen in 7.0 rgb 8 bit and could'nt. Then remembered having problems in cymk space. Went into CS and it happened in rgb 8 bit, I'm stumped as to why and what changed.

 

No problems with printing though, on my end, maybe it's in your color settings?

 

WDA

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nisus,

 

This is not my strongest area...... if the printer is getting incompatible 'Working Space' information either by wrong type of working space (or image mode), color management (wrong embeded or no profile) or conversion, it maybe re-interpreting the image in a very "coarse" (low bit manner).

 

So many variables, monitor & it's profile being used in RGB space, printer mfg RGB CYMK, printer settings, the PS Color settings that could possibly cause this, the monitor display banding I can understand but,I've never had a problem unless the image was rendered with banding or there was some kind of mis-match, improper set up in the color settings.

 

Sorry I can't be more specific-just don't know enough about your hardware and so on.

 

WDA

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Hi WDA,

 

I think you're a bit off topic... I mean the problem is VERY SIMPLE.

I open photoshop, new document, draw a gradient... TADAA Banding...

Print the image (no matter WHAT settings): Banding!

 

It's really a problem IN THE IMAGE... just not sure how it gets there...

 

rgds

 

nisus

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nisus,

 

 

Yes it's in the image. You can only slice up the gradient by 256 in three channels, million+ colors. If you are dealing with a narrow range of just blue it's much less, it's primarily only changing one channels levels. Over a large res area at some point you hit the limits and large or percievable numbes of pixels contian the same data, a step band. Introduce noise to beak up the edges?

 

I don't understand why you are getting obvious print banding. Most printers take low level changes in pixel information and 'dither' and such. There is a contrast threshold that allows smoothing / blending of pixel data verses a defined edge, a gradient in PS should be on the smoothing side. I'm sure your printers are of a very high quality. So.... either the image data is very "coarse" something like being interpreted like a BMP format or been corrupted by a conversion rgb>cymk / profile mismatch. Beyond that I don't know what could be causing it?

 

Is this something that just showed up? Could it be something goofy like the printer is low on ink or in need of maintenance?

 

WDA

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Ah, another vote for breaking up the edges!

 

nisus,

 

Took your image printed it out, no banding in the print version. Took the 'info pallet' and I always do, checked to see if the banding corresponds to RGB color info. Yes it does, perfectly. Meaning that it's in the image and that the pixel depth has been reached, ie can not be defined/refined any further under rgb 8 bit, anyway. 16 bit may yield better results, although I don't know if the gradient algorythm in PS CS actually refines the steps further. But if the image goes through a 8bit conversion, it's back to the 8 bit steps.

 

Check the printer documentation and see if there is anything about minimizing banding or how the images are read and interpreted

 

My display shows the bands, PS 'info' shows the pixel color data of the bands, the printer 'smooth's' those fine edges out. Don't know what else to say, and don't want to fan any "Flames" of your frustration.

 

brgrds

WDA

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Tnx for checking WDA, really appreciated!

 

Pixel depth reached was my explanation to my collegue who pointed it out to me first... But trying to solve the prob was not possible... Our 'printer' - a guy, not a machine and VERY experienced - could not solve it either... awful...

 

I'm just wondering, are we really going back to basics in evolution??? Now photoshop banding like never before... and last week Discreet advices us NOT to render at 3800x7600 anymore, because it's to high (while we've been rendering like this for over 4 years now!!!... ow hell... Give me more Fire!! ,-p)

 

rgds

 

nisus

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So basicly... with better printers, we now really SEE the mistakes that were always around, but were lost in the process... awful...

Gonna find me a non-professional printer... he'll probably be able to print without banding... ;-p

 

rgds

 

nisus

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Hehehehehehe........

 

Discreet.... now they speak the truth. Was there a specific reason/s why, beyond crazy long render times?

 

Your "Printer"- what type of print proccess is being used, always curious ;)

 

The noise and blur seems like the way to go. Would probably work best at the channel level in a sperate document then import gradient image into working image. That should even get the banding past an offset print process, destroy the problem at the source, hehehe (sinister laugh)

 

Evolution- 8 bit lagging way behind 16 bit image tech, under 32 bit and it should be intersting to see how well and long the effects of 64 bit processing takes to effect the lag.

 

Cheers

WDA

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disreet: reasonable render times (MR van be rather fast if you know how to set it up - I do (at last!)) but permanent crashes after SEEING the finished image on screen... Couldn't find a problem, some memory issue... al kinds of memory settings, savings, 3 different type of rams, etc. could not solve the trick... Supposed to be BAD geometry, groups, collapse etc. which was NOT the case, etc etc etc... Solution: don't render so high! Render in seperate passes (we used to do this in m3 but want to save more on post-work... ) Render at 75% and blow p in ps!!! **DUH!!!!**

 

BUT they gave us great support really, only couldn't solve it ,-(

So finally I solved it tweaking RT-bounces etc... ,-p

 

and the banding... well HELL!

 

rgds

 

nisus

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