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OPR Workshops => Difficult => Topic started by: Kerbstone on September 01, 2020, 11:39:41 AM

Title: color advice unrelated to opr
Post by: Kerbstone on September 01, 2020, 11:39:41 AM
If I had an rgb image with an svg filter which was then indexed with 256 colors then converted back to rgb - how would this affect print?
Title: Re: color advice unrelated to opr
Post by: Shadow on September 03, 2020, 05:35:57 PM
does the image look as good on screen compared to the original rgb?
Title: Re: color advice unrelated to opr
Post by: Kerbstone on September 03, 2020, 06:28:06 PM
Yes Shadow
Title: Re: color advice unrelated to opr
Post by: Shadow on September 04, 2020, 04:55:39 PM
Was hoping one of the print masters would weigh in for you. My thinking was ... when I have had to change an image mode more than once, I have not seen any degradation when printing so I thought if your image looked as good as the original, maybe it would print equally as well.
Title: Re: color advice unrelated to opr
Post by: Kerbstone on September 04, 2020, 08:54:49 PM
TY for that Shadow  ;)
Title: Re: color advice unrelated to opr
Post by: Tori803 on September 05, 2020, 08:38:13 AM
I'm not sure I follow what you're trying to do. But any rgb image that is going to be printed will be converted to cmyk which can have a bigger effect on the color. One thing I've learned working for a newspaper is you don't really know how something will look in print until you print a copy. Any special effects that look great on a screen may not translate well to print.

Depending on what you're printing on, degradation may not seem to appear. For example, when I create an ad for newsprint I don't always worry that the client has included a low resolution image (72 dpi) since out highest output on newsprint is only 180 dpi. But if we have a special section printing on better paper I try to get better images from the client. Degradation may not seem to show up, but it is there and every time more changes are made, the worse it can get.
Title: Re: color advice unrelated to opr
Post by: Kerbstone on September 05, 2020, 08:45:45 AM

(https://i.postimg.cc/jCZ0bQXf/for-rana-error-level-analysis.png) (https://postimg.cc/jCZ0bQXf)

https://fotoforensics.com/tutorial-ela.php Thank you so much for that Tori.  I found this tool in GIMP that may be useful to you too.
Title: Re: color advice unrelated to opr
Post by: Kerbstone on September 05, 2020, 08:50:59 AM

(https://i.postimg.cc/Wd7fGsHk/error-anylsis.jpg) (https://postimg.cc/Wd7fGsHk)
Title: Re: color advice unrelated to opr
Post by: Kerbstone on September 05, 2020, 09:40:01 AM
(https://i.postimg.cc/H8JHPBNb/jpg-floating-point-0-25x.jpg) (https://postimg.cc/H8JHPBNb)

(https://i.postimg.cc/nXxbvFn4/jpg-floating-point-0-25x-error-level-analysis-adobe.jpg) (https://postimg.cc/nXxbvFn4)
Error level analysis of an adobe file by gimp. convert to smart file in adobe images coming.
Title: Re: color advice unrelated to opr
Post by: Kerbstone on September 05, 2020, 09:48:07 AM
Error level analysis of an adobe file by gimp. convert to smart file in adobe.
(https://i.postimg.cc/hJSfzDKw/jpg-floating-point-2x-ela.jpg) (https://postimg.cc/hJSfzDKw)
Title: Re: color advice unrelated to opr
Post by: Kerbstone on September 05, 2020, 03:39:20 PM

(https://i.postimg.cc/bSQp0vfk/print3-with-noise.jpg) (https://postimg.cc/bSQp0vfk) image with noise to fix banding and the before and after error level analysis

(https://i.postimg.cc/RNdzvySS/print3-ela.jpg) (https://postimg.cc/RNdzvySS) before


(https://i.postimg.cc/dh0c3638/print3-ela-with-noise.jpg) (https://postimg.cc/dh0c3638) after
Title: Re: color advice unrelated to opr
Post by: Kerbstone on September 05, 2020, 04:25:16 PM

(https://i.postimg.cc/9zmZNwnD/print3.jpg) (https://postimg.cc/9zmZNwnD)

(https://i.postimg.cc/mzwMgTtZ/print3-for-rana.jpg) (https://postimg.cc/mzwMgTtZ)

(https://i.postimg.cc/Wt5gRpBX/print3ela2.jpg) (https://postimg.cc/Wt5gRpBX)
Title: Re: color advice unrelated to opr
Post by: Kerbstone on September 05, 2020, 05:01:46 PM
(https://i.postimg.cc/hJh3x4kj/nearfinalwith-noise-all-except-gaussain-unchecked.jpg) (https://postimg.cc/hJh3x4kj)

(https://i.postimg.cc/T5P98tTP/nearfinal3.jpg) (https://postimg.cc/T5P98tTP)
Title: Re: color advice unrelated to opr
Post by: Kerbstone on September 05, 2020, 05:10:17 PM

(https://i.postimg.cc/hzXjHmHB/nearfinalwith-noise-all-except-gaussain-unchecked.jpg) (https://postimg.cc/hzXjHmHB)

(https://i.postimg.cc/RN5FDNdk/nearfinal3ela.jpg) (https://postimg.cc/RN5FDNdk)
Title: Re: color advice unrelated to opr
Post by: Kerbstone on September 09, 2020, 03:40:17 AM
The error level analysis tool plugin tends to crash on indexed colors.  Converting to rgb should fix this.