116257 - Loading a 150kb png image bloats 15-17mb

Status: RESOLVED DUPLICATE of bug 51028

(Core :: Graphics: ImageLib, defect)

Description

[Navin Gupta]

I will attach the image. Also this image is the mailnews dependency map
posted by alecf in n.p.m.mail-news (if you sort by lines you 
should see it in your thread-pane). 

Also this has nothing to do w/ mailnews code because if I save it locally and 
drag and drop it to a browser window it bloats by same amount - 15-17mb.
I am filing it on you, I will also reasearch a bit, but feel free to assign it 
to the right owner.

Comment 1

[Navin Gupta]

Attachment: image

image that causes bloat.

Comment 2

[Scott MacGregor]

naving, you should file this under the "Browser" product with a component of
"ImageLib"

Comment 3

[Navin Gupta]

Attachment: top callsite report

top callsite report shows that all the allocation is being done in imglib,
as expected.

Comment 4

[Navin Gupta]

Attachment: stack trace for top callsite

Comment 5

[Navin Gupta]

changing component and the owner

Comment 6

[Warner Young]

Isn't this to be expected?  The image is over 7000 pixels wide.  If imglib is
going to display something, it probably has to be converted internally to a
Windows DIB or DDB first.  Depending on the color depth, the DIB/DDB is going to
be 4MB (at 1 byte/pixel) up to 18MB (4 bytes/pixel).

Comment 7

[Navin Gupta]

IE takes like 5-6mb, could be image resolution but I wasn't very sure. 

Comment 8

[Warner Young]

I don't know enough about imglib, so I'm guessing here.  Maybe Mozilla's imglib
isn't using the optimal color depth for the DIB/DDB?  The actual PNG file is
apparently 4bpp, so IE's use of 5-6MB sounds about right.  Maybe Mozilla is
promoting the image to 32bpp (due to transparency?).

Comment 9

[Christian :Biesinger (don't email me, ping me on IRC)]

I don't see the bug here. The image is 7175x743 pixels large. Every image gets
decoded using 4 bytes per pixel (Mac) or 3 bytes per pixel (all others). so for
PC, the expected memory usage (just for the image data itself) is 15,993,075
bytes. (on a Mac: 21,324,100 bytes).

Comment 10

[John Levon]

bug 51028 ?

Comment 11

[Warner Young]

John, yes, this does sound like a dupe (PNG case) of bug 51028.

Comment 12

[Marius Strumyla]

does anyone notices the performance problems scrolling the image?

on two NT boxes that i tested, to scroll right the attached png image takes
forever (~1 minute!) with CPU at 100%. this doesn't happen on another box with Win98

Comment 13

[ArronM (:paper)]

*** Bug 164871 has been marked as a duplicate of this bug. ***

Comment 14

[ArronM (:paper)]

Yes, essentially the same issue as Bug 51028.  We expand all images to 24 bits
per pix minimum, even if they are 8 bit.  3 - 4x memory usage than need be in
those cases.

*** This bug has been marked as a duplicate of 51028 ***