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Gradient banding(?) of vector file in photoshop


ogremydeadbody

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Hello everyone,
Yesterday I encountered something weird which I'm not even sure how to classify, hence the question mark. So, what happened was that I prepared a rather large Photoshop file, about 45000x7000 pixels, 300 dpi, CMYK. Then I inserted a stock vector file onto the canvas through a simple drag and drop, and enlarged it to fit the canvas better. It seemed fine from afar, but when I zoomed in I noticed that the gradients looked rather strange, almost like photoshop didn't know how to process them, and ended up turning them into pixelated ones. What's even stranger to me is that not every gradient looks like this. The little flashes on some of the shards also band slightly, but nowhere near as badly as the rest of them. The lineart of the shards also seems alright.

photoshop.png

I then decided to open the same vector file in illustrator for comparison, partially to check if it's perhaps my computer that has trouble interpreting the gradient. But in Illustrator they seem very smooth.

illustrator.png

I decided to enlarge the file in illustrator, hoping that perhaps it would resolve the issue when inserting the file back into Photoshop. And it kind of did, but then another issue appeared; the flashes changed color and got this weird halo effect. I should perhaps mention that I switched the color mode of the Illustrator file from RGB to CMYK, because when in RGB mode Photoshop interpreted it as blue rather than gray. However, the same problem occured with the RGB file, too, so I don't know if that has anything to do with the issue.

photoshop 2.png

I very rarely work with vector files, so I'm not sure where these issues stem from. I also apologize if I'm being unclear. English isn't my first language, so feel free to ask additional questions and I'll try to answer them to the best of my abilities.
 

ogremydeadbody

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Okay, dismiss that last part about the halo effect, I managed to fix it. Shows up it also appeared in Illustrator when switching from RGB to CMYK, it was just a lot dimmer and I didn't notice it at the time. Switching the darkest point of the gradient to 100% CMYK got rid of it. However, if anyone has an explanation to the first part about the gradient banding, I'd still love to read it.
 

thebestcpu

Guru
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Hi @ogremydeadbody
It would probably help forum members if they had access to your files to give the best recommendations via a file sharing process.
Without that here is my best thoughts on causes and things to try.

With Photoshop being pixel focused there is likely some issues where in the conversions you are not getting the best results. Here are some thoughts to make that a bit smoother

1) Make sure all components are natively in the same color mode e.g. RGB or CMYK and not a mix. Conversions between the modes can create issues
2) Make sure that all components are natively in the same color space e.g. if RGB using sRGB or AdobeRGB etc. Otherwise conversion between color spaces can create issues
3) It apears you have PS set to a large enough set of pixels so that should not be an issue yet enough pixel resolution is important as well
4) Make sure when you bring the AI vector file into PS, do it via the File > Place Embedded command. This will bring the AI object directly into PS as a Smart Object so when you resize etc, it whould go back to AI it doing the resizing and give you the best resolution

There can be other factors that come into play such as viewing conditions. Always view at 100% magnification or larger and preferablly at multiples of 100% magnification to help avoid display artifacts.
Also, PS can create display anomalies whne working with PS documents fo multiple layers (details not provided). To avoid those anomalies, create a stamped Layer of all the Layers and again view at mulitples of 100% will avoid those types of anomalies.

I would give those steps a try and it you don't have good results, then please post the files for examination by forum members to help search for the issue
Hope his helps
John Wheeler
 

JeffK

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I usually don't even attempt at solving technical issues and @thebestcpu is one of the best analysts we have here.
But curiosity got to me and I started to dig into what appears to be a very complex problem Certainly moving a vector based file like Illustrator into a raster based program like Photoshop has an impact. Also running into gamut problems when switching from RGB to CMYK as well as creating complex gradients in 8 bit vs. 16 bit. Dark colors to bright colors also create issues. All of it creates quite a stew.

Here's some of what I found - haven't vetted these solution so your mileage may vary:

- Don't use Illustrator to create your gradients - do your linework in Illustrator and gradient work in Photoshop
- Use either noise or gaussian blur filters to blend the pixels - here's a try I made on your posted image:

1632257494078.png

- Work in 16 bit vs. 8 bit - then stamp all layers together and save as an 8 bit file. Which also brings you back to using Photoshop for gradients since Illustrator only works in 8 bit.

There are other more technical areas at issues but the one that keeps rising to the top is avoiding Illustrator for gradient work.

- Jeff
 

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