Thunderbird embedded jpeg quality sucks due to recompression.  How to fix?

Posted on 2008-10-02
Last Modified: 2012-05-05
Amazingly, there is virtually NO info on the net about this.  It is a very serious problem for photographers like me who like to send clients an e-mail with embedded jpeg images.  It is also a big annoyance when sending embedded screen captures....

When you attach a jpeg to a Thunderbird e-mail, the file content and quality is preserved.  However, when you embed the same image (even a screen capture via cut/paste) Thunderbird seems to be recompressing the image at a VERY low quality.  In order that my embedded jpegs appear decent, I have to save them at a very high quality (level 10 in Photoshop).   This is presumably because a level 10 jpeg can withstand further compression rather well.

Try this (as I believe this is related to the same issue): Take a snapshot of a small application window (ALT+PRINT SCRN).  Paste that into a thunderbird e-mail.  You should immediately notice terrible jpeg artificats due to heavy compression.  Paste the same clipboard content into Photoshop and you won't see any loss in quality.

Is there some hidden setting where I can tell Thunderbird to either avoid recompressing the embedded image, or to do so at a much higher quality?

Question by:kleencoder
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Expert Comment

by:Marc Z
ID: 22627702
Nick, Once you have embedded the image, have you ever looked at the Properties of it? Double click the image, so Properties pops up, go to the Dimensions tab and make sure Actual Size is selected.  Does that help?

I too a screen shot, Pasted it into an html email and it showed up as 1440*900 which is the resolution of my monitor.

If you have better jpg's and you are embedding them, that Properties->Dimensions should be set to Actual Size and not reducing them if that is what you want.  I'll look around to see if there is a certain Preference or setting somewhere that you can set, but you might have to set the Actual size every time, although mine does that for me by default.

What is yours set to?

Expert Comment

ID: 22628738
Other thing you can try saving them as jpg. zip and attach.....

Author Comment

ID: 22628746
Mine is set to actual size.  I always resize my images so they appear of reasonable size in the e-mail--600 pixels wide typically.  I offer galleries of ready-to-email (600-pixel-wide) images that clients can use to embed in their emails.

Look at the following example image linked below.  You will see the awful artifacts around the text on the right hand side compared to the source image on the left.   I realize jpegs are not great for text, but this proves the point that Thunderbird is recompressing the image.

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Expert Comment

by:Marc Z
ID: 22629815
Nick, are the recipients of your emails complaining?

I do see what you are saying in that image.  I am wondering if it's not just the TB program displaying itself badly.  Perhaps not utilizing True Type correctly? If you were to email that screenshot you pasted into TB, does the resulting email change resolution at destination or does your monitor just not display TrueType correctly within TB?  

I just tested, it does look like the resulting pasting of jpg's does mess up the looks of the image.

Hmm, I'll try to take a look through the bugzilla tomorrow and see if they are working on this.

Accepted Solution

kleencoder earned 0 total points
ID: 22642988
Whether it's true-type or not has nothing to do with it because it's a jpeg image, not an actual font rendered by TB.  It's just a screen capture, so I'm just pasting in a 2-day array of pixels (albeit, compressed as per the jpeg standard).

Anyway, I found out that there actually IS a bugzilla report on this.

It says it has been resolved, but it looks like the fix got backed out and is awaiting something else to be updated first.

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Expert Comment

by:Marc Z
ID: 22644879
Thanks kleencoder,

glad you found that bug.

As I read through it, it looks like this one is what is causing you issues.
Might want to keep an eye on that one also.

If you would like to get your points back, no objections from me. Just hit the request attention button in your original post.

Author Comment

ID: 22650480
mtz1of4 yes, I saw that related bug.   Although that might solve the problem, I'm not having an issue with the raw clipboard contents being embedded as a jpeg.  The problem is that when it gets converted to a jpeg by Thunderbird, it gets converted at a very low quality setting (like 50/100 according to bug 384116).  For images that are already in jpeg format, I also don't want them to be recompressed when embedding the jpeg file directly (not from the clipboard).  I believe 384116 covers both of these issues.

Thanks for trying to help.  I'm going to accept my post as the solution.

Expert Comment

ID: 22803839 is fixed with a higher quality JPEG ratio setting. Latest Shredder beta will have the issue fixed. However this results in large JPEG file sizes. PNG would have been the optimum solution.

Expert Comment

ID: 25250833
A client of mine who is a photographer first brought this problem to my attention.  I have struggled to find a solution to this issue for some time now, and I have to second the post from Kavlins:  The best way to attack this is to zip and attach.

Zip or RAR or 7-zip or (pick your flavor) is an excellent way of encapsulating your data so that, during handling and transport by various means or across different types of media, the integrity of the data won't be compromised.  In the case of image files, it preserves image quality, prevents further compression or recompression of the image, and preserves metadata such as IPTC or EXIF.

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