moderated Low quality images #misc


 

I have reported this as a bug at the KDE bugzilla site (https://bugs.kde.org/show_bug.cgi?id=435776). But since it only happens with messages originating from groups.io, I'm bringing it up here.

I use POP3 and KMail2 to process almost all of my email. I have a problem with image quality on messages that originate at the groups.io web site. Here is an example screenshot.



As you can see, the image is all washed out, and the photographed text is hard to read. But it's a rendering problem, and not an image quality problem per se. Here's a screenshot of the same image file, also rendered by KMail. (I selected just the image attachment for display by KMail to make this screenshot.)



Clearly the bug is somewhere in KMail. But it's only triggered by messages that came from grroups.io, so far as I can tell. Is there anything peculiar about the headers that groups.io inserts in outgoing messages that could possibly account for this? Something else about groups.io messages that might affect image quality? Weird metadata in the image file, or something like that?

Any suggestions will be appreciated, and gratefully accepted.
--
David Bryant
Canyon Lake, Texas
https://t-vog.groups.io/g/main    https://davidcbryant.net


Andy
 

David,

It is interesting that the two example files you provide have nearly the same filesize.  But they also include different portions of screen capture, so it's not a fair comparison.  You should also note that the first picture has some text at the top, which is crystal clear and only the stuff below it is washed out -- so maybe the lost quality happened when the file was created (with annotated text), before sending it to a groups.io group.

Andy


 

On Tue, May 4, 2021 at 05:00 PM, Andy wrote:
David,

It is interesting that the two example files you provide have nearly the same filesize.  But they also include different portions of screen capture, so it's not a fair comparison.  You should also note that the first picture has some text at the top, which is crystal clear and only the stuff below it is washed out -- so maybe the lost quality happened when the file was created (with annotated text), before sending it to a groups.io group.
Your vision is good. But I guess I didn't explain myself clearly.
 
The first image is a picture of the message as it is displayed in KMail's "message preview pane" when I ask KMail to show me the formatted HTML message. The text portions of the message are displayed correctly. But the image following the text is all washed out.

I'm not sure If you have studied the structure of an HTML-encoded email message very closely, or not, Andy. Such a message usually consists of several parts.
  • The message headers
  • The plain text version of the message
  • The message in HTML -- <head>(some stuff)</head><body>(some other stuff)</body>, etc. Not quite a web page, but close.
  • One or more embedded image files. Images may be attached, or, more frequently, defined as a ref="http://..." item on a remote server somewhere.
Here's a screenshot illustrating the structure of today's "Digest" as I received it from the beta group. The message headers are in the first "body part", marked with a folder icon.


KMail lets me select any segment of the message and display only that single piece. That's how I created the second screenshot in my original message. Both screenshots were taken from the same program, KMail. In the first one I told KMail to display both text and and image data. In the second one I just asked to see the image file. My question (probably for Mark) is if there is something unusual about the image files sent out by groups.io, because this doesn't happen with messages I receive from other web sites.
--
David Bryant
Canyon Lake, Texas
https://t-vog.groups.io/g/main    https://davidcbryant.net


Derek Milliner
 

At a guess, I'd say that the PNG image has an alpha channel that KMail's mishandling when it's displaying an inline image? Try taking a look in something like GIMP...


 

On Tue, May 4, 2021 at 10:23 AM David Bryant <david@...> wrote:
I have reported this as a bug at the KDE bugzilla site (https://bugs.kde.org/show_bug.cgi?id=435776). But since it only happens with messages originating from groups.io, I'm bringing it up here.


When images need to be resized, we do so using ImageMagick. Nothing special.

Mark