Color differences jpeg and png

[DearDeparted]

I'm puzzled by the color difference between an exported jpeg (dull) and a png (bright) and hope someone can help me understand what is going on.

I'm maintaining a website and part of it is uploading images created from a (sRGB) psd file from the designer. I edit some text inside that psd and export it for uploading to the website.

The previously uploaded images from this psd by others are all png images (bright).

What I see happening is this:

1. On my monitor I see the colors as they should be and like the images on the website
   
2. Exporting the image in png is the same
   
3. Exporting the image as jpeg quality 100 gives the same result as the png when viewed in a color managed image viewer like Geeqie, but dull in the default Linux Mint image viewer which has no color management
   
4. Uploading the png is okay, same bright colors
   
5. Uploading the jpeg gives dull colors.
   

I would expect the png and jpeg to be the same. All are simple sRGB images. So what am I missing here?

I'm using a Dell monitor and calibration via Spider 4.

[Redraw]

Hello
Not hijacking your post just I'm very interested in this,

the same image saved as
I often get png as a little bit too darkish
and jpg as washed out, little too bright
have tried many many different settings in Gwen and some in Gimp nothing changes and have not found common ground for images that fail

sometimes I will re-adjust image in Gimp until it looks OK in an image viewer (gwenview), this is not a fix only a quick work-around so I'll be watching this with much interest to hear of a fix for you

[plumbergp]

2nd hijacker here. Ha.

Similar problem here. Did some editing in GIMP and sent the photo to one forum. 

Surprised and shocked to see the dull/saturated photo in that forum when compared to what I see on my PC screen.

Due to different image quality standards on different platforms?

Thanks.

[DearDeparted]

I have been seeing differences between browsers, that is a known fact. For instance I had an image exported from within Darktable as jpeg. It looked like the way it should be, but in Firefox the colors were a lot duller than in Chrome which showed it correctly. Then I did a complete reset of Firefox and that helped. But it this case older uploads looked good, but only in png, not in jpeg.

The jpeg I exported from Gimp looks good in Geeqie, but in Gwen and the Linux Mint XViewer it looks dull. But that might have something to do with color management, reading or not reading a color profile within an image. But then again, all these programs and browsers work with sRGB as default... ?????

The change in colors after uploading could also have something to do with the image processor on servers. Mostly used are Imagick and GD Library.

I just found this post, so it could have something to do with the image processor:
https://github.com/Intervention/image/issues/707

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(07-03-2019, 11:24 PM)Redraw Wrote: have tried many many different settings in Gwen and some in Gimp nothing changes and have not found common ground for images that fail

sometimes I will re-adjust image in Gimp until it looks OK in an image viewer (gwenview), this is not a fix only a quick work-around so I'll be watching this with much interest to hear of a fix for you

I don't think adjusting the image so that it looks good in Gwenview is a solution. Could you view that same image you adjusted in Geeqie? Curious how it looks then.

[rich2005]

Putting colour calibration and most users having a too bright monitor to one side.
Take your troublesome pair of png / jpeg and use Imagemagick to list the properties for each.

Code:

identify -verbose image.ext

and compare for difference. If there are big difference, then some investigation needed



For the same RGB image exported in each format by Gimp there are small differences. Jpeg is biased towards vision rather than a RGB monitor display, but it is minor. A good (my opinion) recent article https://parametric.press/issue-01/unraveling-the-jpeg/

If they come out virtually identical, then surely the problem is software related.

Try asking the question here: https://discuss.pixls.us/

[DearDeparted]

Hi Rich,

I checked and the differences are very very small. But perhaps the question is why do different image viewer show the same image in a different way, while all being sRGB images? I'm not sure.

So both png and jpeg exported from the same psd file. In Gwen the png looks okay, but the jpeg is dull. In Geeqie they both look okay. In XViewer the jpeg again is dull. And uploading both to a website makes the png look okay but the jpeg dull.

[rich2005]

I am using kubuntu 18.04 and Gimp 2.10.12 here so a few more colour management options.

Using the lenna.png standard sRGB image and changing the profile to PhotoGamutRGB icc, exporting that as a jpeg.

Comparing images in a web browser (slimjet - chromium based) the jpeg is very-very slightly brighter than the png. So a colour profile might have a difference, but if both are the same sRGB ???
Both compare the same in Imagemagick. Both look the same in Gimp but then this notebook computer display is not colour profiled. All by eye and subjective. Viewing in XnViewMP - no difference that I can see.

It might just be your colour profiled monitor

[Redraw]

@rich2005

The colour profiled monitor isn't an issue here,

I did find some things after trying the other suggestions also with the viewing apps and there is some differences,

Gimp, inkscape, okular and smplayer and xnviewmp these showed the images as good quality

Gwenview, Krita and Geeqie these show the images as washed out colours.

( yes I know some apps are NOT dedicated jpg or png image viewing apps as such )
that's not important it's how different the images show in the different apps and I wonder .. why ?
if it's not the monitor
what is the common or difference between the good viewing apps and the not so good viewing apps ?

@plumbergp

I don't know how these issues are in a Windows machine and the apps there, Honeyview would be only only I know of, what viewers do you use, thanks.

Thanks to all for the many ideas and things to try.

[plumbergp]

(07-04-2019, 11:42 PM)Redraw Wrote: @plumbergp

I don't know how these issues are in a Windows machine and the apps there, Honeyview would be only only I know of, what viewers do you use, thanks.

Thanks to all for the many ideas and things to try.

The comparison was via GIMP and a forum image (dont know what viewer they are using there).

Since you mentioned this, tried the photo using different viewers and results as below.

Win explorer preview, GIMP and Win Photos images are about the same.

Win media player and VLC images are darker.

All viewed on the same monitor (LG HD).

[Redraw]

@plumbergp thanks for trying out the other image viewers,

extra info might help someone trying for work this out,

I don't know enough about the small details that go into apps so I'm no help in that.

But it is interesting has this problem only started lately ?
I don't see this question asked in the past ?,

did and what 'something' changed ?
and it seems to affect Window users and Linux users of different distros also, any apple users ?

Am I on the correct with this thought ?
If the solution is to find a image viewer that is (lack of a better word ) compatible with gimp, now the past viewers are playing up then get that image viewer that works properly , as rich2005 said Viewing in XnViewMP - no difference that I can see.

Tricky Tricky