Output quality - Contrast ?

[B.Douille]

See below, on top a picture modified by XnView v1.0 18 and at bottom the original JPEG.
The modified picture shows less brightness, brilliance.

20260717_004731_Screenshot_20260717_004731_Gallery.jpg

I noticed the change after testing the resize feature so I updated XnView and made the above comparison using the convert feature to jpg with 100% quality. There shouldn't be any visible change.
I wonder if I already observed something similar with XNconvert or with ResizeMe. Maybe a pb with libraries.

[Kadet]

Me too. Converion/resize to any type of file makes the new image less bright.
But not all files.
This is about the “Color Profile” which is not copied to other files except JXL. On PC, JXL is no different from the original JPG photo, but on mobile it is slightly different (less than converted files to other formats).

And by the way, on XnMobile there is no information about the color profile as in XnPC.

[xnview]

please check v19

[B.Douille]

With v19 the image converted (JPEG, 100% quality) seams a bit more brilliant but still a difference vs the original.

Moreover, very strange: With XnView mobile, the difference between the original and the modified copy is obvious. With Google Photos or Samsung Gallery both looks similar but the original becomes more brilliant after 1 second and this doesn't happens with copies. Using File Commander or BubbleUPnP this phenomenon doesn't happens and pictures seams very similar.
I even copied the 3 files on my PC and compared visually and with the histogram. There is nothing really visible despite the 3 files are different in size.

[Kadet]

Profile Color is now copied (not from HEIC) from the source file, but still one tested file JPG -> JPG don't look identical on Android (on PC all is good).
Take a zip file with samples from here: https://drive.google.com/file/d/1221GOs ... sp=sharing

[B.Douille]

Very strange to me. This is highly dependent on the renderer, the App used to display images.
I used EXIFtool Pro for Android to export the set of metadata and compare. See below.

20260719_183423_Screenshot_20260719_183423_MobiOffice.jpg

There are few differences, mainly some fields missing on the copy but seems to be Manufacturer’s ? However there are nothing like JFIF on the original.
Maybe need to use EXIFtool on PC with option -b or other options to see what's really different.

[B.Douille]

Update: I just tested different images, original vs modified by XnView Mobile, modified by XnConvert and modified by ResizeMe. Except for the last, results are less brightness. ResizeMe preserves the quality, contrast of the original.
I checked if a picture modified by the editor integrated in Samsung Gallery would influence the brightness. The answer is no, original quality is well preserved

Next, I downloaded some of my recent pictures from Photoweb Cloud (ex-Joomeo) and compared to the originals, still on my phone. No visible difference (what I expected from this French provider )

Last, I tested Chromcast as well as Mediacast on my TV, using Google Photos and Samsung Gallery. In all cases there are no visible difference on the TV screen.
But, at the time I disconnect, the original becomes brighter instantly on my phone whereas the modified copy doesn't cchange. How can this happens...

[xnview]

Moreover, very strange: With XnView mobile, the difference between the original and the modified copy is obvious. With Google Photos or Samsung Gallery both looks similar but the original becomes more brilliant after 1 second and this doesn't happens with copies. Using File Commander or BubbleUPnP this phenomenon doesn't happens and pictures seams very similar.
I even copied the 3 files on my PC and compared visually and with the histogram. There is nothing really visible despite the 3 files are different in size.

could you send me the original and output file from your phone?

[B.Douille]

Here is link to download 3 samples I mentioned in my original post :
- Original
- Modified with v18
- Modified with v19
The differences are mostly visible on the top of the car and on the sidewalk of the windows.
The samples provided by Kadet show similar differences, visible on the lights in the metro.

https://www.grosfichiers.com/xmadgt5sg7n

[xnview]

Here is link to download 3 samples I mentioned in my original post :
- Original
- Modified with v18
- Modified with v19
The differences are mostly visible on the top of the car and on the sidewalk of the windows.
The samples provided by Kadet show similar differences, visible on the lights in the metro.

Thanks, you see the difference only on android (gallery), right? could you send me the orignal converted by resizeMe that works?

[B.Douille]

Find below a link to download sample pictures
- The version modified by ResizeMe
- Another original and a version modified by XnView and by ResizeMe.

Very curiously, today for my pictures the big difference only appears on the Google pictures app. The Samsung Gallery app only shows lighter differences. However, it's visible with the picture sent by Kadet. I really don't understand.
Also, what I found yesterday, using ResizeMe isn't that obvious. The difference vs original is ~equivalent to those modified with XnView mobile. That's why I include another set of pictures I used for testing.

https://www.grosfichiers.com/fuFZCDw8dwz

[xnview]

Also, what I found yesterday, using ResizeMe isn't that obvious. The difference vs original is ~equivalent to those modified with XnView mobile. That's why I include another set of pictures I used for testing.

ResizeMe remove the icc profil, v19 keeps it but remove the MPF (HDR) datas

If you copy the files on PC, do you see difference?

Please check v20

[B.Douille]

Hello Pierre, 1st of all I should apologize. My phone was on night mode, which explains some artifacts on lightning. Sorry.

This said, I compared modified by v20, modified by v19, no visible differences vs original picture. That's ok for me.
I checked also on a PC, Win 11, XnView MP as well as Photos and it’s all good.