934389 - Insert Image displays wrong size, if DPI > 100% on MS Win

Status: NEW

(MailNews Core :: Composition, defect)

Description

[Anje]

User Agent: Mozilla/5.0 (Windows NT 6.0; rv:25.0) Gecko/20100101 Firefox/25.0 (Beta/Release)
Build ID: 20131025151332

Steps to reproduce:

Reports of problems with image size are being reported in GetSatisfaction/Mozilla Messaging..see link below:
https://getsatisfaction.com/mozilla_messaging/topics/too_large_image_display_in_thunderbird_24_0_1?page=1

Open Write new message
Insert > Image
does not matter if you use Menu Bar or Formatting Bar.




Actual results:

the display is larger than actual pixels
Cannot resize to get back to normal.


Expected results:

The image size should not be larger than the original image size.

Comment 1

[Charles Younger]

With updates ver 24.0.1 and 24.1.0, inserted images no longer appear at the correct size. Rather than being displayed at the original pixel dimensions they're larger (and out of focus). For example, on my 1920x1200 monitor a 700 pixel wide image displays at 960 pixels or so. 

I've tried restarting with addons disabled, reinstalling, and installing an earlier ver. without result. 

View/Zoom/Reset and Zoom Text Only have no effect.

In Config Editor the default for "mail.enable_automatic_image_resizing" is set to "true." Changing the setting has no effect. 

Whether I use Insert/Image at the top menu or use the insert icon on the formatting bar and choose "Image" makes no difference.

"Image preview" shows the actual dimensions. Under the "Dimensions" tab "Actual Size" is selected and "pixels" is shown.

Images appear overly large when inserted. They remain so when messages are saved and Thunderbird closed and rerun, and if emailed to myself and opened it in Thunderbird. If I view the image online in my Gmail inbox or save it to a folder and open it in an image viewer it appears correctly. 

There's also a separate (possibly related?) malfunction I've experienced with these latest versions. The "Choose color for text" icon in the formatting bar no longer works most of the time. Clicking on "Format" and "Text Color" in the top menu does work. 

Thanks,

C.M.Younger

Comment 2

[[e-mail]]

I have the same problem. It started with version 24.1.0. If I attach an image or paste it in into a message the display is larger than actual pixels by about 1.8X. eg A 700 pixel image uses approximately 1300 pixels. If I copy the image from the email message and paste it into a photo editor program though it is still 700 pixels. Another problem is that if I hit the CNTR - keys the text will get smaller but not the image.

Comment 3

[WADA:World Anti-bad-Duping Agency]

Same problem as bug 933171?

Comment 4

[WADA:World Anti-bad-Duping Agency]

It may be by porting of following change in Gecko/Firefox(22?) to Tb 24.
  layout.css.devPixelsPerPx = -1.0
Do you see your problem with "layout.css.devPixelsPerPx = 1.0"?
How about with "layout.css.devPixelsPerPx = 1.1"?

Comment 5

[Charles Younger]

Changing  to "layout.css.devPixelsPerPx = 1.0" did return the image back to its original size. All of Thunderbird's internal text in lists and menus is much smaller however.

Comment 6

[Charles Younger]

With "layout.css.devPixelsPerPx = 1.1" imges were less large. I didn't get a pixel count.

Comment 7

[Charles Younger]

As mentioned in  bug 933171 I too have Windows text display set larger than the default. In my case 140%.

Comment 8

[WADA:World Anti-bad-Duping Agency]

(In reply to Charles Younger from comment #5)
> Changing  to "layout.css.devPixelsPerPx = 1.0" did return the image back to
> its original size. 
> All of Thunderbird's internal text in lists and menus is much smaller however.
It's normal and expected phenomenon.
As your display is high resolution type, OS's DPI is set as 140% of standard 96DPI by deault, in order to show text/graphics in larger/readable size on screen.
To show Tb's window, menu, text etc. in required size or in readable size, "layout.css.devPixelsPerPx = Magnification(=140% in your case) * 1.0" is needed. 
"layout.css.devPixelsPerPx = -1" means "Use OS's DPI setting". 

Because Mozilla had bug of "Internal devPixelsPerPx value which is used in actual display from OS's DPI == integer", "(96DPI*140%)/96DPI==1.4 => rounded up to 2" had happened when "layout.css.devPixelsPerPx = -1" is set.
This problem was resolved, so "layout.css.devPixelsPerPx = -1" was defaulted.

How about with "layout.css.devPixelsPerPx = 1.40"?

(In reply to Charles Younger from comment #6)
> I didn't get a pixel count.
What phenomenon do you call "didn't get a pixel count"?

Problem like following occurs?
- Text size in menu, in mail display is as expected,
  but image is shown in larger size than actual image data size of image data.
- When image is inserted to HTML, HEIGHT/WIDTH in generated <IMG> tag
  is larger than actual image data size of the image data.
It's merely phenomenon like following?
  "pixel count of image area displayed on physical screen" which is reported by utility
  == 140% of "actual HEIGHT/WIDTH of image data".

Comment 9

[Charles Younger]

My 140% dpi is a custom setting. 

With "layout.css.devPixelsPerPx = 1.4" images again appear much larger. Again I don't have a pixel count, by which I mean I don't exactly how much larger than their original size than they're being displayed. Text appears more normal however.

An images sourced online inserted in HTML in an email, at  "layout.css.devPixelsPerPx = 1.4" appears correctly. At 1.0 it appears smaller than it should.

Comment 10

[WADA:World Anti-bad-Duping Agency]

(In reply to Charles Younger from comment #9)
> With "layout.css.devPixelsPerPx = 1.4" images again appear much larger.
> Text appears more normal however.
Phenomenon like following?
  If layout.css.devPixelsPerPx = 1.4 && OS's DPI serring = 140% of 96DPI,
  upon mail display,
  - Text is normaly expanded to 140%.
  - Image is expanded to 140% * 140% (== 1.96 times).

> An images sourced online inserted in HTML in an email, at  "layout.css.devPixelsPerPx = 1.4" appears correctly.
> At 1.0 it appears smaller than it should.
Phenomenon like following?
  If layout.css.devPixelsPerPx = 1.0 && OS's DPI serring = 140% of 96DPI,
  upon insert image in HTML mail composition,
  - Text is normaly expanded to 140%.
  - Image is shrinked to (100%/140%=1.0/1.4==0.71) times.
Is HEIGHT/WIDTH of generated <IMG> tag always correct?
What is shown as "size" at "Image Properties" of the inserted image?

Comment 11

[Charles Younger]

Correction.

If layout.css.devPixelsPerPx = 1.4 (Windows 7 DPI set at 140%) then HTML inserted image (from web) is expanded 1.4 times (a 175 pixel wide image displays at 244 pixels) and text appears normal.

If layout.css.devPixelsPerPx = 1.0 (Windows 7 DPI set at 140%) then HTML inserted image (from web) appears correctly at its original size and text appears shrunken.

Image Dimensions "Actual Size" shown remains at the correct original 175 pixels whether it's set to 1.0 or 1.4.

Comment 12

[Anje]

Comment for the record, maybe it will assist.
I am not experiencing any issues with images.
OS = Windows Vista
My computer is set up with resolution 1920 x 1080 pixels.

I've just checked my Thunderbird config settings for layout.css.devPixelsPerPx and it says -1.0 (minus one).

selected an image stored on computer under properties it says:
width="2048" height="1536"
Horizontal and vertical resolution 200 dpi

Insert > image and check pixelsit says width="2048" height="1536"
Add image; it looks correct.
Message source of Sent copy and received copy show correct size width="2048" height="1536".

Comment 13

[Anje]

My computer display settings DPI scaling is set as default = 96 DPI

Comment 14

[WADA:World Anti-bad-Duping Agency]

Regression by bug 844604 which was landed on Firefox 22? (see bug 933171 commet #5)

Comment 15

[WADA:World Anti-bad-Duping Agency]

(In reply to Charles Younger from comment #11)
> If layout.css.devPixelsPerPx = 1.4 (Windows 7 DPI set at 140%) then HTML
> inserted image (from web) is expanded 1.4 times (a 175 pixel wide image
> displays at 244 pixels) and text appears normal.
> If layout.css.devPixelsPerPx = 1.0 (Windows 7 DPI set at 140%) then HTML
> inserted image (from web) appears correctly at its original size and text
> appears shrunken.
> Image Dimensions "Actual Size" shown remains at the correct original 175
> pixels whether it's set to 1.0 or 1.4.
It sounds for me that phenomenon is;
  Image is zomed as expected by "devPixelsPerPx = 1.4",
  but Text is somehow not zoomed by "devPixelsPerPx = 1.4" nor "Win7 7 DPI = 140%".
If font, "DPI=140% of MS Win" is perhaps applied to font rendering by "MS's module returns (9 pt * 140% pixels) to 9 pt request". And it may depend on used API or used parameter of API.

Try following, please.
(A) Zoom
 (1) Change first zoom size from .3 to .4
        toolkit.zoomManager.zoomValues = .3,.5,.67,.8,.9,1,1.1,1.2,1.33,1.5,1.7,2,2.4,3
     => toolkit.zoomManager.zoomValues = .4,.5,.67,.8,.9,1,1.1,1.2,1.33,1.5,1.7,2,2.4,3
 (2) View -> Zoom -> check "Zoom Text Only"
     (or browser.zoom.full=false)
 (3) View -> Zoom -> Zoom In
 Note: IIUC, zoom size is "per site" and is remembered in "per site".
       In Tb, it's perhaps "per mail".
(B) Font size
 (1) Tools/Options/Display, Formattig, Advanced
     Size/Minimum font size : 16 -> 22 ( 16*140%=22.4 )
 (2) View HTML mail with "View/Message Body As/Simple HTML" (ignore font setting in mail)

Comment 16

[WADA:World Anti-bad-Duping Agency]

Confirming per detailed observation by bug opener.

Comment 17

[WADA:World Anti-bad-Duping Agency]

FYI.
> http://msdn.microsoft.com/en-us/library/windows/desktop/dd464660%28v=vs.85%29.aspx#high_dpi_features_in_windows
"API to declare DPI awareness" is No in Win-XP but Yes in Win7(Vista or later).
Fx 22 or later on Win may use it for font rendering request. Or Gfx on Win after Fx 22 may apply devPixelsPerPx/1.4(DPI value) to font because OS already applies DPI=140% to font if Firefox.

Comment 18

[WADA:World Anti-bad-Duping Agency]

FYI.
Depends on of Bug 844604 : Bug 857089, Bug 911409, Bug 924068 
Bug 911409(icon in menu is larger than text in menu) is for 24 branch, and cause of problem may be same or similar.

Comment 19

[WADA:World Anti-bad-Duping Agency]

Charles Younger,
Do you see similar phenomenon to Bug 911409 on icon in UI(menu) of Tb 24 with DPI=140%/layout.css.devPixelsPerPx=1.4?
Do see any difference between "DPI=140%/layout.css.devPixelsPerPx=1.4" and "DPI=140%/layout.css.devPixelsPerPx=-1" in any of mail display, image insertion, and nUI(meu)?

Comment 20

[WADA:World Anti-bad-Duping Agency]

(In reply to Anje from comment #12)
> Comment for the record, maybe it will assist.
> I am not experiencing any issues with images.
> OS = Windows Vista
> My computer is set up with resolution 1920 x 1080 pixels.
> layout.css.devPixelsPerPx and it says -1.0 (minus one).
> Insert > image and check pixelsit says width="2048" height="1536"
> Add image; it looks correct.
(In reply to Anje from comment #13)
> My computer display settings DPI scaling is set as default = 96 DPI

To Anje(bug opener):
Original report of comment #0 is never problem what you actually experienced or saw in your environment?

If it's right, your case is important evidence that this bug won't occur with DPI=96dpi(100%) and layout.css.devPixelsPerPx=-1(and 1.00) at least on Vista.

Do you see any problem similar to this bug(insert image) or Bug 933171(mail view) or Bug 911409(UI/menu) with layout.css.devPixelsPerPx=1.25, with keeping OS's DPI=96dpi(100%)?

Comment 21

[Charles Younger]

With first zoom size in toolkit.zoomManager.zoomValue changed from .3 to .4 and both Size and Minimum font size set at 16, and looking at an HTML message in my inbox, set to view as simple HTML, text appears at a good, normal size. Images don't appear, of course. With both Size and Minimum font size set at 22, text size increases. Both are clear and readable. I didn't try the intermediate sizes. Don't know what I should be looking for. 
        
With layout.css.devPixelsPerPx=1.4 (DPI=140%) I don't see any arrows in menus (?).

I see no difference between "DPI=140%/layout.css.devPixelsPerPx=1.4" and "DPI=140%/layout.css.devPixelsPerPx=-1"

Comment 22

[WADA:World Anti-bad-Duping Agency]

(In reply to Charles Younger from comment #21)
> Images don't appear, of course.
I thought we all are trying to know something about phenomeon of "image is shown in 140% size as expected but text is somehow shown in 100% size"... :-)

Anyway, we now perhaps know followings.
  When layout.css.devPixelsPerPx=1.4 and OS's DPI=140%,
  image is always shown in 140% size as expected, and ;
  (A) with Zoom Text Only + zoom size = 1.4 :
      Text is shown in 1.4 times size, so mismatch with image size doesn't occur.
  (B) with Minimum font size=22 pixel(16px * 140%), when usual font size=16 pixel :
      Text is shown in 1.4 times size, so mismatch with image size doesn't occur.
I guess phenomenon is as follows.
  till Fx 23/till Tb 21 :
    Font rendering result returned from OS is always 100% regardless of OS's DPI=140%.
    By devPixelsPerPx=1.4, it's shown in 140% size.
  In Fx 24 :
    Font rendering result returned from OS is always 140% based on OS's DPI=140%.
    So shrink to 100%/140% first, 
       if web page display : then zoom to 1.4 times using devPixelsPerPx value,
                                                      or using OS's DPI=140%. 
       if UI               : forget to zoom to 1.4 times
  In Tb 24 : same thing as Fx 24/UI occurs in mail view or mail composition
     
> With layout.css.devPixelsPerPx=1.4 (DPI=140%) I don't see any arrows in menus (?).
No "arrow for expanding sub menu" in dropdown menu at Menu Bar(File, Edit, View, Go, ...)?
Do you use non-standard Theme?
If Aero, it may be diferent.

Comment 23

[Charles Younger]

(In reply to WADA from comment #22)
> (In reply to Charles Younger from comment #21)
> > Images don't appear, of course.
> I thought we all are trying to know something about phenomeon of "image is
> shown in 140% size as expected but text is somehow shown in 100% size"... :-)

That's why I still don't understand why you asked me to view the message using simple HTML, since that precludes images from appearing. Guess I must be missing something.

> No "arrow for expanding sub menu" in dropdown menu at Menu Bar(File, Edit,
> View, Go, ...)?
> Do you use non-standard Theme?
> If Aero, it may be diferent.

I'm using a slightly modified Aero theme yes, *but* I didn't really think of the small right-pointing triangle symbols as "arrows" when I read the comment. My mistake. They don't appear bigger than they should when devPixelsPerPx=1.4, no.

Comment 24

[WADA:World Anti-bad-Duping Agency]

(In reply to Charles Younger from comment #23)
"simple HTML" in that context ==
   choice of "Simple HTML" at /View/Message Body As/ menu in mail viewing.
This is to rule out confusion in test by <font size="...> or "style="font-size:..."> of HTML mail. Tb ignores style request in HTML mail if "Simple HTML mode". 

> "small right-pointing triangle symbols" don't appear bigger than they should when devPixelsPerPx=1.4, no.

Same problem as Bug 911409(icon in menu is larger than text in menu) occurred on Tb 24 in your environment?
Or same problem as Bug 911409(icon in menu is larger than text in menu) did not occur on Tb 24 in your environment?
(I think ", no." means ",so answer to my original question is no.", so I guess latter case, but I'm not sure. I'm not native English speaker, so it's very hard to understand correct meaning of "They ... don't ... , no.". In Japanese, [ Reply of "No" to "They ... don't ...?" ] == [ entire "They ... don't ..." is false ].)

Comment 25

[WADA:World Anti-bad-Duping Agency]

Charles Younger, do you see problem of Bug 911409 on Fx 24 or Fx 25 in your environment with keeping OS DPI=140%?
Is there any difference among devPixelsPerPx = -1, 1.4, and 1.0?

Comment 26

[Charles Younger]

> (I think ", no." means ",so answer to my original question is no.", so I
> guess latter case, but I'm not sure. I'm not native English speaker, so it's
> very hard to understand correct meaning of "They ... don't ... , no.". In
> Japanese, [ Reply of "No" to "They ... don't ...?" ] == [ entire "They ...
> don't ..." is false ].)

The last "no" was redundant. I used it for emphasis. Hmm. There is, in colloquial American English usage, a grammatical form where a sentence can end in the word "not" to mean the negation of what was said previously. It's something of a rhetorical device. The "not" is unexpected and somewhat disorienting and generally indicates that the previous words were meant sarcastically. Such usage may be made with humorous intent, or even with some malice. I believe it's only become a widely used form in the relatively recent past (20 years?).

Comment 27

[Charles Younger]

(In reply to WADA from comment #25)
> Charles Younger, do you see problem of Bug 911409 on Fx 24 or Fx 25 in your
> environment with keeping ?
> Is there any difference among devPixelsPerPx = -1, 1.4, and 1.0?

In Firefox 25. w/OS DPI=140%:

devPixelsPerPx = -1 is the default, and just looks normal to me. 
w/devPixelsPerPx = 1.0 text and images both become much smaller.
w/devPixelsPerPx = 1.4 text and images both look the same as at -1

The arrows scale proportionally. They don't look overly large.

Comment 28

[WADA:World Anti-bad-Duping Agency]

(In reply to Charles Younger from comment #27)
> > do you see problem of Bug 911409 on Fx 24 or Fx 25?
> In Firefox 25. w/OS DPI=140%:
> The arrows scale proportionally. They don't look overly large.
If so, report it to Bug 911409, please.

Bug 911409 is Thema dependent issue? (Aero may be different)
Or Bug 911409 is already fixed in Fx 25?

Do you see this bug in Tb trunk nightly(daily) build?
> http://ftp.mozilla.org/pub/mozilla.org/thunderbird/nightly/latest-comm-central/
To protect from daily use profile corruption by nightly, test with new profile, please.
  Create new Tb profle, define dummy news account only(e.g. servername=news.news.news).
  => "Local Folders" is created, so you can do mail related test.

Comment 29

[WADA:World Anti-bad-Duping Agency]

Use ZIP build in nightly test, please. You can do test by UNZIP only.

Comment 30

[Charles Younger]

(In reply to WADA from comment #29)
> Use ZIP build in nightly test, please. You can do test by UNZIP only.

Forgive me for not understanding. I've created a new news account. I don't understand how to do a test. There are two files that I might download. 

thunderbird-28.0a1.en-US.win64-x86_64.tests.zip	
thunderbird-28.0a1.en-US.win64-x86_64.zip

Comment 31

[WADA:World Anti-bad-Duping Agency]

(In reply to Charles Younger from comment #30)
Following is "ordinal" nightly build for nightly tesyers. .tests.zip may be debug build.
> thunderbird-28.0a1.en-US.win64-x86_64.zip
However, there is no need to test with nightly for this bug any more, because Bug 911409 seems Win8 only problem.

Comment 32

[WADA:World Anti-bad-Duping Agency]

FYI.
> Bug 844604 merely changed default of layout.css.devPixelsPerPx to -1 from 1.0.
> Bug 820679 is meta bug with following Bug Summary.
>     (win-hidpi) [tracking] support for hi-dpi display
>     (resolution scale factors > >  100%) on desktop (non-Metro) Windows
>   Metro Windows == Windows 8 (perhaps)
>     http://en.wikipedia.org/wiki/Windows_8
>       In particular, these changes included a touch-optimized Windows shell
>       based on Microsoft's "Metro" design language, (snip)
> Bug 911409 may be Win8 only problem.
>   Bug 911409 : Menu arrows are very large in Windows 8.1 with DPI above 100%

Comment 33

[WADA:World Anti-bad-Duping Agency]

Bug 894216 refers to "Use Windows XP style DPI Scaling" option, which is relevant to font rendering and is perhaps feature from Vista.
See Bug 894216 Comment #2, Bug 894216 Comment #4, and Comment #17.
"Use Windows XP style DPI Scaling" setting in Win 7 :
  https://pattersonsupport.custhelp.com/app/answers/detail/a_id/13103/~/how-to-change-dpi-settings-in-windows-7
See also following document.
  http://www.kynosarges.org/WindowsDpi.html
    http://www.kynosarges.org/WindowsDpi.html#XPStyle
    http://www.kynosarges.org/WindowsDpi.html#Virtual
  http://www.kynosarges.org/GuiDpiScaling.html
  http://msdn.microsoft.com/en-us/library/dd464660%28v=VS.85%29.aspx

Do you see problem in Tb 24 with OS DPI=140%, layout.css.devPixelsPerPx=1.4, and with "Use Windows XP style DPI Scaling" enabled?

Comment 34

[WADA:World Anti-bad-Duping Agency]

FYI.

> http://www.kynosarges.org/WindowsDpi.html#Virtual
>   Windows Vista DPI Virtualization
>     Microsoft therefore disables DPI virtualization by default,
>     unless you choose a pixel density greater than 120 DPI.
Check with OS DPI=120%(115.2dpi), layout.css.devPixelsPerPx=1.1152 or 1.115 may be helpful.

Bug summary of Bug 894216 :
> Bug 894216 - Consider using device pixel scale
>              if "Use Windows XP style DPI Scaling" is unchecked
This bug in Tb 24 may be relevant to Bug 894216, because Bug 894216 seems problem in Fx22 and later, and because "Windows Vista DPI Virtualization" is enabled and "Windows XP Style DPI Scaling" is disabled on Windows 7 when OS DPI=140%(134.4dpi) is set.

Comment 35

[WADA:World Anti-bad-Duping Agency]

My guess in previous comment may be wrong, because bug 933171 was for problem on Win-XP.
  Windows-XP, Tb 24, OS DPI=125%(120dpi)

Comment 36

[GDPR]

This is still happening as of version 102.3.0 on Windows 11.

Pasting screenshots into OneNote or in GitHub Issues, for example, they're pasted in the correct size (100% or their size).

Pasting inline in Thunderbird Compose window always makes the images larger than they should (at 100% Zoom), and the image seems to be actually sent with the increased size, to the recipient.

Related: bug 933171

Comment 37

[Wayne Mery (:wsmwk)]

(In reply to GDPR from comment #36)

Related: bug 933171

duplicate?

Comment 38

[GDPR]

The bug I submitted (bug 934389) is still happening.

Seeing the suggestion on the bug 933171, of the changes in Config Editor, I confirm those values are what I already have.

Set: 'layout.css.devPixelsPerPx' to default, a negative -1.0
Set: 'mail.uifontsize' = 12

Changing the Font Size of the composer, or Zooming In/Out doesn't really fix the image issue. If I zoom out, what happens is that the font also decreases, together with the image.

Thank you.

Comment 39

[Anje]

(In reply to GDPR from comment #38)

The bug I submitted (bug 934389) is still happening.

Seeing the suggestion on the bug 933171, of the changes in Config Editor, I confirm those values are what I already have.

Set: 'layout.css.devPixelsPerPx' to default, a negative -1.0
Set: 'mail.uifontsize' = 12

Changing the Font Size of the composer, or Zooming In/Out doesn't really fix the image issue. If I zoom out, what happens is that the font also decreases, together with the image.

Thank you.

Please confirm you have this:

Set: 'layout.css.devPixelsPerPx' to default, a negative -1.0
Set: 'mail.uifontsize' = 12

Then tell me what you see here:
Menu app icon > Font Size - what does it say for the ?px setting ?
Is the font size generally in Folder Pane, Message List look OK ?

Then 'Help' > 'TRoubleshooting Information'
scroll down to Important Modified Preferences
look for all lines begining with 'font'
copy all those 'font' lines and paste them into this bug report.

You may have settings that conflict.

Comment 40

[GDPR]

Please confirm you have this:

Set: 'layout.css.devPixelsPerPx' to default, a negative -1.0
Set: 'mail.uifontsize' = 12

Yes, I said in my comment above that I have those exactly like that.

Menu app icon

What's "menu app icon" ?

Is it the "hamburger / 3 stacked lines" icon at the top-right?

If I click there, it shows "12px" in the Font setting.

Is the font size generally in Folder Pane, Message List look OK ?

I think all those look fine, and expected. Nothing too big or anything. Normal font size.
My "Density" setting is "Default" (the middle option).

copy all those 'font' lines and paste them into this bug report.

font.internaluseonly.changed false
font.size.fixed.el 14
font.size.fixed.x-cyrillic 14
font.size.fixed.x-unicode 14
font.size.fixed.x-western 14

Thanks!

Comment 41

[Anje]

Thanks for info .
Please work through the following to make sure all the font settings for reading and writing emails are set at same size. It's to ensure nothing is conflicting within Thunderbird regarding any font size.
Generally, people like reading and composing mail to be slightly larger than what is set for Message list etc. As you have font fixed width set at 14- lets use that option.

• Settings > General
• Scroll to 'Language & Appearance'
• click on 'Advanced' button

Set font sizes for Latin - western

• Fonts for: select 'Latin'
• Proportional - Size: set 14
• Monospace - Size: set 14
• Minimum font size - set 12 (allows a small change but stops tiny font)

Set font sizes for Cyrillic.

• 'Fonts for': select 'Cyrillic'
• Set identical sizes for everything as indicated for 'Latin'

Set font sizes for unicode

• Fonts for: select 'Other Writing Systems' (it's at the bottom of drop down list)
• Set identical sizes for everything as indicated for 'Latin'

Reselect

• Fonts for: select 'Latin'
• Click on 'OK'

Now check composition setting

• Settings > Composition
• Scroll to 'HTML Style'
• Size: set 'Medium' and your set up will auto use size 14 as your medium - what you see when typing email automatically.

Check theme:

• Left pane - bottom - click on 'Addons & Themes' jigsaw icon
• What theme have you been using up until now ?
• Select to use either 'Dark' or 'Light' theme, but not 'System Theme'

Test:
Open a new Write message
TYpe some text - move to new line
use the 'Insert > Image' option.
click on 'Choose file' and locate image
Before you select it - hover over image and note the dimensions

select jpg image and click on 'open'
select 'attach this image to the message'
click on 'Dimensions' tab - set 'Actual size'
Make a note of what it says for the Actual Size pixel size for height and width.

Leave two lines.
Add same image again but this time use a slightly different option.
'Insert > Image'
click on 'Choose file' and locate image
select jpg image and click on 'open'
select 'attach this image to the message'
click on 'Dimensions' tab - this time select 'custom size' and 'constrain'
If your computer is auto using a scale greater then 100% as typically used by computers with 4k then reduce eg: height by one third or even to half size and width gets auto altered or vis versa - you do not manually alter both.
Example: if width or height is 600px then reduce to 400px or 300px

click on 'OK'
SAve as a draft, but keep Write window open.

I'm looking for feedback/info on :
What theme you were previously using and what theme you are currently using?

Image stored on computer Dimensions pixel size - is it the same as stated in 'Actual Size' when using Insert > Image > dimensions tab?
What were both dimensions?

When you used 'Custom & contrain' in second copy of image what dimensions did you use ?

Please post an image of the 'Write' message so we can see what you can see before the email is sent.
At top of this bug there is an 'Attachments' section which you may need to expand to see the 'Attach new file' button.

Send email to yourself or another of your email addresses to see what the received email looks like.

Comment 42

[GDPR]

Hello
I appreciate the time to write all these instructions.

I made the font changes as requested, for the 3 "Fonts for" options.

Proportional - Size: set 14
-- this was previously 17

Monospace - Size: set 14
-- this was already 14

Minimum font size - set 12 (allows a small change but stops tiny font)
-- this was "None"

Size: set 'Medium' and your set up will auto use size 14 as your medium
-- already "Medium"

What theme have you been using up until now ?
System Theme (which is light)
I changed to "Light".

Then restarted Thunderbird.

The text in the emails became a lot smaller (since I changed the settings from 17 to 14), but the issue with the images in the Composer persists, after all these changes.

I believe what might be happening is that the images of the screenshots are indeed "big", but when I open those images on the Gallery app / Image Editor, it somehow scales down a bit (while on Zoom 100%), to compensate the DPI.
If I open the image on Chrome, it seems to show the image as big as in Thunderbird Composer.

Scaling the images to 75% "fixes" the Composer issue, which is what I did when I followed your steps. I multiplied the Actual Size by 0.75, and used the result, and then the image looks perfect in the Composer. I'll attached everything here in the next minutes.

Comment 43

[GDPR]

Attachment: 1 - The Image.jpg

Comment 44

[GDPR]

Attachment: 2 - Pasted in Composer, versus Thunderbird UI in the background.jpg

Comment 45

[GDPR]

Attachment: 3 - Insert image - Actual Size.jpg

Comment 46

[GDPR]

Attachment: 4 - Insert image - 75 percent Size.jpg

Comment 47

[GDPR]

Attachment: 6 - After sending email (looks exactly the same as Composer).png

Comment 48

[GDPR]

Attachment: 5 - Before sending email.png

Comment 49

[GDPR]

Attachment: 7 - In the Gallery app (looks as expected, at 100%).png