[SOLVED] Thunderbird Mail: bad image quality in displayed attachments

[Moem]

I'm using Thunderbird Mail 68.4.1 on Mint Cinnamon 19.3.
I've noticed that images that I receive as well as images that I've sent to others look very bad in the Message Preview window. Opening the message in its own window does not improve things. The images look as if they're viewed in 256-bits colour.
Because an image says more than a thousand words, here's a screenshot. On top is the image as seen in an image viewer, and below is the way Thunderbird shows it. This is the exact same image.
It's not a great image, resolution-wise, but that's not the point. You can see that the colours in the version shown at the bottom are harsh and unnatural.

Does anyone have any pointers on how to resolve this?

[gittiest personITW]

Hi Moem,

Have you got an extension that plays around with your pictures automatically such as Shrunked Image Resizer?

[Moem]

No. This is all that I'm using:

[gittiest personITW]

So, if you email a picture to yourself, download it to your hard drive, then open the picture up in an image viewer, checking the resolution/colours and possibly a hash, has the picture been changed?
I know you said it happened in Preview but just checking it is just preview.

[Moem]

If I mail myself an image, it looks bad in the preview. If I save it under a new name and open it in an image viewer, it looks fine and identical to the one I attached to the email. In other words, emailing the image does not change the image size, the file size, the resolution, or the colour depth.
Not sure what you mean by 'a hash'.

[gittiest personITW]

As I'm sure you've looked throught the settings etc, the only one I can find that might make a difference is Settings/Advanced/General/'Hardware Acceleration'.

Also - is it only one email account that shows the low def image or all accounts in Thunderbird?
The hash = MD5 or whatever your preference was - but it doesn't matter if you know there is no difference.

If you change the default picture viewer does it make a difference? For instance when I preview a picture in Thunderbird it is opened up by Nomacs which shows the true image.

[Moem]

As I'm sure you've looked throught the settings etc, the only one I can find that might make a difference is Settings/Advanced/General/'Hardware Acceleration'.

Good one. But that's not it.

Also - is it only one email account that shows the low def image or all accounts in Thunderbird?

All accounts.

The hash = MD5 or whatever your preference was - but it doesn't matter if you know there is no difference.

That's good that it doesn't matter, because I still don't know what you mean. Is that a property that guarantees the identity or the integrity of the file, or something like that?

If you change the default picture viewer does it make a difference? For instance when I preview a picture in Thunderbird it is opened up by Nomacs which shows the true image.

Good idea. I would like to try that but I don't know where any of them live. I was already trying to change it to Pix. But where is it located?

[absque fenestris]

Good idea. I would like to try that but I don't know where any of them live. I was already trying to change it to Pix. But where is it located?

File System > usr > bin > pix

[Moem]

Thank you. I've changed the setting to that, then restarted the application, and the setting is retained but I don't see a difference.

[Pippin]

Regarding checksum of the picture:

Code: Select all

# sha256sum pic.png
497e0e66e66065cd71b9035fac4410a72a75ccd9b3a3207807c70249959f0822  pic.png

This checksum is unique and can be used to verify that pic.png is original.

[Moem]

Right, thank you. I'm not going to bother with that.

[gittiest personITW]

Right, thank you. I'm not going to bother with that.

No you're right. It was only if you thought that the picture had been changed which it hasn't.

I tried to see earlier on if I had the same issue but I use Nomacs as the default jpeg viewer.
If you go into file manager and right click a picture - open with - then you can change the default viewer (then change it back to what you want afterwards).

[Moem]

.png images are set to be viewed in Pix... and they're equally crappy. Curiouser and curiouser!
Also interesting: this is the setting the way I found it. Note that it does not mention an application for .jpg. It does mention one for .jpeg but that does not seem to change the results.
.png, .jpg and .jpeg all look like 256 color images when seen in Thunderbird.

[absque fenestris]

@ Moem: please check whether Firefox or another browser displays websites correctly. Thunderbird works with HTML - just like any other browser.
And I had exactly this problem (poor rendering) after a not so successful Cinnamon update.
My post in the Mint Forums is a good verification: if you don't see different shades of gray* in the posts from @smurphos or mine - the operating system has a problem ...

viewtopic.php?f=47&t=307787&start=20

*different shades of gray... Sorry - was not meant as a joke, but in the print industry shades of gray are relevant...

[Moem]

@ Moem: please check whether Firefox or another browser displays websites correctly.

Yup... just fine.

[absque fenestris]

@ Moem: please check whether Firefox or another browser displays websites correctly.

Yup... just fine.

So at least it has nothing to do with the operating system. No solution now - but you have to start looking somewhere ...

[Moem]

That's exactly right... finding out what the problem isn't, is useful too!

[rene]

This is a relatively random suggestion but I wonder if you have been experimenting with colour profiles, for example in the "xiccd" sense" that Karlchen recently found a problem with on 19.3. I would expect the quickest test of this scenario to be an entirely new user profile, although you'll of course have to configure TB a bit again to be able to retrieve a message showing the symptom...

[Moem]

Hmm, I'll have to look into that... it might not be all that random. I did at one time choose a specific colour profile to solve a problem with colours in browsers...

[Moem]

Solved! Rene set me on the right track... in the config editor of TB, I found (by searching for settings that contained 'color') a setting for color profile. It was set to something different than my general color profile. Now I do not know whether it was a wrong color profile that TB was using or that it's just best when it's the same as the one set for your monitor, but I changed it to be the same as my general color profile and that fixed it!

Setting in TB (it's the setting above the one that's highlighted)

General color profile setting