Open Bug 872082 Opened 11 years ago Updated 2 years ago

further PNG compression benefits

Categories

(Firefox :: General, enhancement)

23 Branch
enhancement

Tracking

()

People

(Reporter: elliotwilliams7, Unassigned)

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(4 files)

User Agent: Mozilla/5.0 (Windows NT 5.1; rv:23.0) Gecko/20130514 Firefox/23.0
Build ID: 20130514040203

Steps to reproduce:

Compression can help make things faster and help save disk space on a computer that is running out of storage space. Compression allows things to load faster due to the smaller file size then the computer can process it faster.


Actual results:

I've compressed some of the files using Punypng and I've converted RGB files that are gray style to gray style like they should be.


Expected results:

Over all compression allows for a better experience on the web and a better future for the web and can benefit many people who have slow computers due to lack of ram and CPU power as well as disk size like on a SSD for example where space is limited due to expense of a SSD.
Attached file More Files!
Priority: -- → P3
Attachment #749347 - Attachment mime type: application/octet-stream → application/zip
Attachment #749868 - Attachment mime type: application/octet-stream → application/zip
Severity: normal → enhancement
Component: Untriaged → General
Summary: Compression Benefits → further PNG compression benefits
Is this bug only about PNG files, or about everything?
Priority: P3 → --
(In reply to Aleksej [:Aleksej] from comment #2)
> Is this bug only about PNG files, or about everything?

It's just basically the graphic files right now and they are mostly PNG files I think unless you can compress any thing else.
They can probably be reduced from 16-bit grayscale to 8-bit grayscale without any apparent degradation, and the 72dpi pHYs chunk isn't terribly useful and can be removed.  See also bug #843838, bug #631392, and bug#644087.
I don't want to do bulk image swaps in patches. Please instead attach a script to convert the files locally.

But, really, if you're keen on working on this I'd much prefer we fix this permanently by optimizing images at packaging time. (eg bug 631392)
Elliot: perhaps you missed comment 5. Please provide a script to optimize these images, instead of the actual changed images.
How would I go about doing that though?
Start by listing the precise steps you use to convert a single image.
I go to http://punypng.com/ and I use that to do some of the compression and then with any gray style or black or white images I use gimp to get more results and I convert them to gray style.
Oh yes I forgot once I convert them to gray style I then use Punypng again to compress any thing else from the gray style process
A shell script using a tool like pngcrush I what I had in mind.
OS: Windows XP → All
Hardware: x86 → All
I've just announced pngzop-1.0.0 to the png-mng-implement at lists.sf.net mailing list.  It is like pngcrush but uses zopfli compression.  For the branding files attached to this bug, pngzop outperforms Punypng by about six percent:
 -rw-r--r-- 1 glennrp visitor 135206 Jul  1 20:00 about-background_pngzop.png
 -rw-r--r-- 1 glennrp visitor  53962 Jul  1 20:00 about-logo_pngzop.png
 -rw-r--r-- 1 glennrp visitor  23476 Jul  1 20:01 about_pngzop.png
 -rw-r--r-- 1 glennrp visitor   1728 Jul  1 20:01 about-wordmark_pngzop.png
 -rw-r--r-- 1 glennrp visitor   5762 Jul  1 20:01 icon48_pngzop.png
 -rw-r--r-- 1 glennrp visitor   8667 Jul  1 20:01 icon64_pngzop.png
Two of the files have smaller sliding windows (zlib windowBits) when processed
with pngzop.  pngzop is licensed with the zlib license plus UCITA disclaimer.
I forgot to mention that you can get pngzop from pmt.sourceforge.net
I ran pngzop on all of the valid *.png files in a Firefox checkout from the mercurial repo.  There are about 26 that aren't pngs (several are jpegs, most are
text files containing something like "Fake PNG", and some are empty).  33 are APNG files.  2604 are normal PNG files, totaling 9758285 bytes.  pngzop reduced those to 8334917 bytes, for an 8.5 percent improvement in compression.  I didn't try find and recompress any data URL files.
14.5 percent improvement, not 8.5.  pngzop actually does more than recompressing with zopfli; it also removes the alpha channel from all-opaque images and reduces all-gray images from color to grayscale.  It also optimizes the zlib "CMF" bytes which advises the decompressor when it can use a smaller window instead of the 32-kbyte window that zopfli always requires.
Assignee: nobody → glennrp+bmo
Status: UNCONFIRMED → ASSIGNED
Ever confirmed: true

The bug assignee didn't login in Bugzilla in the last 7 months, so the assignee is being reset.

Assignee: glennrp+bmo → nobody
Status: ASSIGNED → NEW
Severity: normal → S3
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