Author Topic: [BBD] Strange color tint in newly created TIFF thumbnails  (Read 420 times)

bekesizl

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[BBD] Strange color tint in newly created TIFF thumbnails
« on: January 10, 2021, 03:15:10 PM »
I recently converted some older JPG files with Topaz JPEG2RAW AI to TIFF files.
IMatch imported these files to the database, but they show a strange color tint, which is more clearly visible in the smaller thumbnails, especially in the sky.
This tint is only visibible as a thumbnail. In the viewer the files show now difference in color.

Can I do something against it? I set RAW processing to "photools.com", but otherwise most of my settings are default.

The original JPG file is about 2,5MB. The converted TIFF is 42MB.

Mario

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Re: Strange color tint in newly created TIFF thumbnails
« Reply #1 on: January 10, 2021, 03:54:05 PM »
Thumbnails are not color-managed by default. Do you use a color profile in your TIF.
Has your software embedded multiple thumbnails / previews in the TIFF? A TIFF can contain multiple images in various resolutions and even different color spaces.
Skies are always tricky, especially when downsizing from 12,16,40,80 Megapixel to 300 pixel size. A lot is lost during such resize operations and color fringes or other artifacts can appear. This is inevitable.

Creating a 42 MB TIFF from a 2.5 MB JPEG file does not seem to be very efficient?
Which kind of TIFF is that, which color model, which compression settings, number of layers, ...

bekesizl

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Re: Strange color tint in newly created TIFF thumbnails
« Reply #2 on: January 10, 2021, 05:01:36 PM »
Efficiency is one thing. I don't want to use it on all old JPG photos, but on the best it might be worth.
It is doing some "AI magic" to get some more details out of JPG photos.

The TIF file shows a color profile in ECP and has a ProPhoto color space. It is uncompressed RGB.

[IFD0]          Subfile Type                    : Full-resolution image
[IFD0]          Image Width                     : 3135
[IFD0]          Image Height                    : 2336
[IFD0]          Bits Per Sample                 : 16 16 16
[IFD0]          Compression                     : Uncompressed
[IFD0]          Photometric Interpretation      : RGB
[ICC_Profile]   Device Mfg Desc                 : little cms
[ICC_Profile]   Profile Description             : ProPhoto
[ICC_Profile]   Device Model Desc               : ProPhoto


It most probably has to do with the ProPhoto colorspace, as if I save it to AdobeRGB, the thumbnail looks much better.
Changing the compression to ZIP reduces file size to 37MB, LZW compression creates bigger files with 46MB.

It is not critical to have it right, it just looks strange currently.
If it is only a problem at me, than leave it like it is. It is probably not worth spending too much time with this issue.

Mario

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Re: Strange color tint in newly created TIFF thumbnails
« Reply #3 on: January 10, 2021, 05:19:03 PM »
Reducing a file to 1/10th of its dimension for thumbnails will inevitable introduce some artifacts or slight color changes in complex areas like sky.
Have you enabled color management for the File Window to see if this makes a difference?

bekesizl

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Re: Strange color tint in newly created TIFF thumbnails
« Reply #4 on: January 10, 2021, 05:35:35 PM »
Thank you!

I didn't know about this possibility.
I found it under Preferences - Application, enabled it and now these thumbnails colors show up correctly.

Mario

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Re: Strange color tint in newly created TIFF thumbnails
« Reply #5 on: January 10, 2021, 05:47:26 PM »
There might be a slight performance price to pay.

bekesizl

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Re: [BBD] Strange color tint in newly created TIFF thumbnails
« Reply #6 on: January 10, 2021, 06:28:53 PM »
I will remember to change back the setting, if I will feel the performance drop, as there won't be many folders with files like that.