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PNGCRUSH a Directory of Images

By David Walsh on September 24, 2009

One easy way of reducing website load time is by optimizing your images. PNG graphics are often more bloated than they need to be so using PNGCRUSH should be a no-brainer. PNGCRUSH's basic usage provides only single-file-crushage but I've created a script that crushes PNGs in directories recursively.

The Bash Script

#!/bin/sh
for png in `find $1 -name "*.png"`;
do
	echo "crushing $png"	
	pngcrush -brute "$png" temp.png
	mv -f temp.png $png
done;

Do whatever you can to compress your images so that your website will load as quickly as possible. PNGCRUSHing your images does not cause a loss of quality -- only a loss of excess file size! PNGCRUSHing my images saved over 120KB of bloated imagery for the recent redesign.

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Discussion

Dimitar Christoff
heh, this post is so engrish: “so that your website load as quickly” and “does not cause a lose of quality”. mootools crew must be whipping you hard then :)

pngcrush… was this something you found on your mac thingie? most inconsiderate of “normal” windows users :D
David Walsh
Holy crap. In my defense this was a really late night post. Weak. My bad.
Robbo
Totally untested, but for windows users, as long as everything is in the one spot….

Create a batch file called “crush.bat”
Put the following code in it.

@echo off
for /f “tokens=*” %%x in (‘dir /b *.png’) do (
echo “crushing %%x”
pngcrush -brute “%%x” temp.png
move /Y temp.png “%%x”
)

Then run it.
Ben
Is there a way to do this with PHP? Or something a bit more practical?
David Walsh
@Ben: What’s impractical about this?
Ben
@David Walsh: I don’t know how to run bash scripts :)
David Walsh
Oh — in that case, try this:

http://pornel.net/imageoptim/en
rick
It’s even easier than that, pngcrush supports * for selecting images to crush. Try: ‘pngcrush -d “/Users/rd/crushedimages/” *.png’ to crush ALL png images in the current directory and put the resulting files in “/Users/rd/crushedimages/” (change this to a directory of your choosing!
jon wilson
i think this was a great post. it has helped me much. thank you
Daniel X. Moore
Very useful script!
vulgarbulgar
In terms of usability and performance, under windoes, it doesn’t get better than this for a gui – http://pnggauntlet.com

a great feature is that you can simply drag/ drop images, and it will ‘smash’ them,a nd overwrite the original files on the fly.

for example, pull your entire website to a local folder, search for *.png in win explorer, then simply drag/ drop the query results into pnggauntlet, making sure to check the ‘overwrite original files’ box, and let it smash down the file size.

i just tested this workflow on a massive ecommerce website (about 2700 png’s worth about 40mb) and saved a whopping 3mb. of course, who knows how well the originals were optimized, but nonetheless, it’s a great result.

another great feature is that it can optionally convert from jpg, tiff, gif and bmp to png.
RagingSloth
I was searching for some information on jpgcrush and google assumed I meant pngcrush… Anyway for anyone who is interested I have several tutorials on this subject (in python) one of which will make use of multiple processors (which saves quite a bit of time if you have a tonne of pngs.)

http://www.ragingsloth.com/softwareEng/PNGOptimizerIndex.html
Ali Robertson
Simplest way to do this.

1. Create a folder for executables which will go into your PATH directory reference.
2. Open folder containing PNGs you want to crush
3. shift + right click in empty space in folder, “open command window in folder”
4. type “pngcrush -d “crushed” *.png
5. close command window and go to newly created ‘crushed’ folder, which now contains your optimised PNGs.
Ali Robertson
Simplest way to do this.

1. Make sure that pngcrush.exe is in a folder which is mentioned in the PATH directory reference, so it can be used from the command line.

2. Open folder containing PNGs you want to crush.

3. shift + right click in empty space in folder, “open command window in folder”

4. type “pngcrush -d “crushed” *.png

5. close command window and go to newly created ‘crushed’ folder, which now contains your optimised PNGs.
files
How to get it to abort if file size will be INCREASED?!
| pngcrush 1.7.9 | Copyright (C) 1998-2002,2006-2010 Glenn Randers-Pehrson | Copyright (C) 2005 Greg Roelofs | This is a free, open-source program. Permission is irrevocably | granted to everyone to use this version of pngcrush without | payment of any fee. | Executable name is pngcrush | It was built with libpng version 1.2.42, and is | running with libpng version 1.2.46 - July 9, 2011
| Copyright (C) 1998-2004,2006-2010 Glenn Randers-Pehrson, | Copyright (C) 1996, 1997 Andreas Dilger, | Copyright (C) 1995, Guy Eric Schalnat, Group 42 Inc., | and zlib version 1.2.3.3, Copyright (C) 1998-2002 (or later), | Jean-loup Gailly and Mark Adler. || Warning: versions are different between png.h and png.c || png.h version: 1.2.42 || png.c version: 1.2.46 | It was compiled with gcc version 4.4.4 and gas version 2.9.5(?). Recompressing wut.png Total length of data found in IDAT chunks = 548746 color counting (-cc option) is not supported. Removed the pHYs chunk. unknown chunk handling done. IDAT length with method 11 (fm 0 zl 2 zs 2) = 2435942 IDAT length with method 12 (fm 1 zl 2 zs 2) = 951323 IDAT length with method 13 (fm 2 zl 2 zs 2) = 905037 IDAT length with method 14 (fm 3 zl 2 zs 2) = 1016476 IDAT length with method 15 (fm 4 zl 2 zs 2) = 858259 IDAT length with method 16 (fm 5 zl 2 zs 2) = 846721 IDAT length with method 17 (fm 0 zl 1 zs 0) = 697832 IDAT length with method 18 (fm 1 zl 1 zs 0) = 797697 IDAT length with method 19 (fm 2 zl 1 zs 0) = 755660 IDAT length with method 20 (fm 3 zl 1 zs 0) = 859270 IDAT length with method 21 (fm 4 zl 1 zs 0) = 761716 IDAT length with method 22 (fm 5 zl 1 zs 0) = 753877 IDAT length with method 23 (fm 0 zl 1 zs 1) = 697832 IDAT length with method 24 (fm 1 zl 1 zs 1) = 797697 IDAT length with method 25 (fm 2 zl 1 zs 1) = 755660 IDAT length with method 26 (fm 3 zl 1 zs 1) = 859270 IDAT length with method 27 (fm 4 zl 1 zs 1) = 761716 IDAT length with method 28 (fm 5 zl 1 zs 1) = 753877 IDAT length with method 29 (fm 0 zl 2 zs 0) = 673435 IDAT length with method 30 (fm 1 zl 2 zs 0) = 765510 IDAT length with method 31 (fm 2 zl 2 zs 0) = 731611 IDAT length with method 32 (fm 3 zl 2 zs 0) = 835291 IDAT length with method 33 (fm 4 zl 2 zs 0) = 735487 IDAT length with method 34 (fm 5 zl 2 zs 0) = 729097 IDAT length with method 35 (fm 0 zl 2 zs 1) = 673435 IDAT length with method 36 (fm 1 zl 2 zs 1) = 765510 IDAT length with method 37 (fm 2 zl 2 zs 1) = 731611 IDAT length with method 38 (fm 3 zl 2 zs 1) = 835291 IDAT length with method 39 (fm 4 zl 2 zs 1) = 735487 IDAT length with method 40 (fm 5 zl 2 zs 1) = 729097 IDAT length with method 41 (fm 0 zl 3 zs 0) = 654550 IDAT length with method 42 (fm 1 zl 3 zs 0) = 710763 IDAT length with method 43 (fm 2 zl 3 zs 0) = 694884 IDAT length with method 44 (fm 3 zl 3 zs 0) = 791240 IDAT length with method 45 (fm 4 zl 3 zs 0) = 694167 IDAT length with method 46 (fm 5 zl 3 zs 0) = 692165 IDAT length with method 47 (fm 0 zl 3 zs 1) = 654550 IDAT length with method 48 (fm 1 zl 3 zs 1) = 710763 IDAT length with method 49 (fm 2 zl 3 zs 1) = 694884 IDAT length with method 50 (fm 3 zl 3 zs 1) = 791240 IDAT length with method 51 (fm 4 zl 3 zs 1) = 694167 IDAT length with method 52 (fm 5 zl 3 zs 1) = 692165 IDAT length with method 53 (fm 0 zl 4 zs 0) = 587966 IDAT length with method 54 (fm 1 zl 4 zs 0) = 695367 IDAT length with method 55 (fm 2 zl 4 zs 0) = 672502 IDAT length with method 56 (fm 3 zl 4 zs 0) = 771732 IDAT length with method 57 (fm 4 zl 4 zs 0) = 675596 IDAT length with method 58 (fm 5 zl 4 zs 0) = 670186 IDAT length with method 59 (fm 0 zl 4 zs 1) = 634611 IDAT length with method 60 (fm 1 zl 4 zs 1) = 698306 IDAT length with method 61 (fm 2 zl 4 zs 1) = 688376 IDAT length with method 62 (fm 3 zl 4 zs 1) = 785595 IDAT length with method 63 (fm 4 zl 4 zs 1) = 680116 IDAT length with method 64 (fm 5 zl 4 zs 1) = 674963 IDAT length with method 65 (fm 0 zl 5 zs 0) = 567961 IDAT length with method 66 (fm 1 zl 5 zs 0) = 659745 IDAT length with method 67 (fm 2 zl 5 zs 0) = 651320 IDAT length with method 68 (fm 3 zl 5 zs 0) = 745437 IDAT length with method 69 (fm 4 zl 5 zs 0) = 648498 IDAT length with method 70 (fm 5 zl 5 zs 0) = 645942 IDAT length with method 71 (fm 0 zl 5 zs 1) = 615134 IDAT length with method 72 (fm 1 zl 5 zs 1) = 667126 IDAT length with method 73 (fm 2 zl 5 zs 1) = 669886 IDAT length with method 74 (fm 3 zl 5 zs 1) = 762645 IDAT length with method 75 (fm 4 zl 5 zs 1) = 658031 IDAT length with method 76 (fm 5 zl 5 zs 1) = 655619 IDAT length with method 77 (fm 0 zl 6 zs 0) = 560413 IDAT length with method 78 (fm 1 zl 6 zs 0) = 618874 IDAT length with method 79 (fm 2 zl 6 zs 0) = 623842 IDAT length with method 80 (fm 3 zl 6 zs 0) = 710951 IDAT length with method 81 (fm 4 zl 6 zs 0) = 618249 IDAT length with method 82 (fm 5 zl 6 zs 0) = 619695 IDAT length with method 83 (fm 0 zl 6 zs 1) = 606769 IDAT length with method 84 (fm 1 zl 6 zs 1) = 627807 IDAT length with method 85 (fm 2 zl 6 zs 1) = 643727 IDAT length with method 86 (fm 3 zl 6 zs 1) = 730353 IDAT length with method 87 (fm 4 zl 6 zs 1) = 629654 IDAT length with method 88 (fm 5 zl 6 zs 1) = 630925 IDAT length with method 89 (fm 0 zl 7 zs 0) = 558547 IDAT length with method 90 (fm 1 zl 7 zs 0) = 605505 IDAT length with method 91 (fm 2 zl 7 zs 0) = 612292 IDAT length with method 92 (fm 3 zl 7 zs 0) = 695889 IDAT length with method 93 (fm 4 zl 7 zs 0) = 608946 IDAT length with method 94 (fm 5 zl 7 zs 0) = 610519 IDAT length with method 95 (fm 0 zl 7 zs 1) = 604538 IDAT length with method 96 (fm 1 zl 7 zs 1) = 614662 IDAT length with method 97 (fm 2 zl 7 zs 1) = 631610 IDAT length with method 98 (fm 3 zl 7 zs 1) = 714922 IDAT length with method 99 (fm 4 zl 7 zs 1) = 620061 IDAT length with method 100 (fm 5 zl 7 zs 1) = 621519 IDAT length with method 101 (fm 0 zl 8 zs 0) = 555261 IDAT length with method 102 (fm 1 zl 8 zs 0) = 589149 IDAT length with method 103 (fm 2 zl 8 zs 0) = 597092 IDAT length with method 104 (fm 3 zl 8 zs 0) = 676219 IDAT length with method 105 (fm 4 zl 8 zs 0) = 596852 IDAT length with method 106 (fm 5 zl 8 zs 0) = 598205 IDAT length with method 107 (fm 0 zl 8 zs 1) = 600862 IDAT length with method 108 (fm 1 zl 8 zs 1) = 597438 IDAT length with method 109 (fm 2 zl 8 zs 1) = 614670 IDAT length with method 110 (fm 3 zl 8 zs 1) = 693766 IDAT length with method 111 (fm 4 zl 8 zs 1) = 606835 IDAT length with method 112 (fm 5 zl 8 zs 1) = 607756 IDAT length with method 113 (fm 0 zl 9 zs 0) = 554346 IDAT length with method 114 (fm 1 zl 9 zs 0) = 578629 IDAT length with method 115 (fm 2 zl 9 zs 0) = 587438 IDAT length with method 116 (fm 3 zl 9 zs 0) = 665646 IDAT length with method 117 (fm 4 zl 9 zs 0) = 586698 IDAT length with method 118 (fm 5 zl 9 zs 0) = 588334 IDAT length with method 119 (fm 0 zl 9 zs 1) = 599719 IDAT length with method 120 (fm 1 zl 9 zs 1) = 586780 IDAT length with method 121 (fm 2 zl 9 zs 1) = 603901 IDAT length with method 122 (fm 3 zl 9 zs 1) = 683089 IDAT length with method 123 (fm 4 zl 9 zs 1) = 595879 IDAT length with method 124 (fm 5 zl 9 zs 1) = 597310 IDAT length with method 125 (fm 0 zl 1 zs 3) = 2246417 IDAT length with method 126 (fm 1 zl 1 zs 3) = 876458 IDAT length with method 127 (fm 2 zl 1 zs 3) = 801576 IDAT length with method 128 (fm 3 zl 1 zs 3) = 940918 IDAT length with method 129 (fm 4 zl 1 zs 3) = 753268 IDAT length with method 130 (fm 5 zl 1 zs 3) = 741504 IDAT length with method 131 (fm 0 zl 4 zs 3) = 2245807 IDAT length with method 132 (fm 1 zl 4 zs 3) = 876189 IDAT length with method 133 (fm 2 zl 4 zs 3) = 801449 IDAT length with method 134 (fm 3 zl 4 zs 3) = 940635 IDAT length with method 135 (fm 4 zl 4 zs 3) = 753015 IDAT length with method 136 (fm 5 zl 4 zs 3) = 741282 Best pngcrush method = 113 (fm 0 zl 9 zs 0) for temp.png (1.02% IDAT increase) (1.02% filesize increase)
CPU time used = 47.830 seconds (decoding 2.470, encoding 45.050, other 0.310 seconds)
files
4 months and no-one’s answered me… This problem really annoys me. It seems that pngcrush’s missing some packing methods…
Joshua McGee
Useful script! Thank you. I’d suggest changing

for png in find $1 -name "*.png";

to

for png in find $1 -iname "*.png";

in order to catch files with extensions such as .PNG and .Png.
Thomas Hunter II
Looks like someone “borrowed” your script:

http://www.wulf.co.nz/running-pngcrush-on-a-recursive-directories/

David Walsh
Everyone steals from me :(
Wulf Solter
Hey now Thomas, that’s a bit of a dick allegation! And a huge let down after I saw http://davidwalsh.name in a list of my site’s backlinks! If I’d found David’s post I would gladly have used his tools rather than spend a few minutes writing my own which I then posted to my site to save it should I need it again. But, you know, if a famous guy said a similar thing before me and I didn’t see or hear it, then I “must” be stealing it. Ugh.

The two scripts aim to achieve the exact same goal using the same most obvious choice tools (find, do while, mv), and use the same most obvious variable names – ‘temp’ for the temp file and ‘png’ for the singular entry in the list of pngs. If you tasked 100 competent developers with this, 95 of them would have a very similar script, and the other 5 scripts wouldn’t work.

I’ll take it as the best compliment that my shitty little bash script can be confused as coming from *the* David Walsh, even if mine has slightly better parameter handling :p

Chris Wadge
Just a suggestion, but it probably makes sense to nice this if running on a live server. Additionally, you can speed this up *a lot* on a multicore box by passing this through xargs.

sloppp

says “illegal option n” or something like dat

this works for me

pngcrush -d crushed_png *.png
cp crushed_png/*.png .
rm -rf crushed_png

joe

UBUNTU / DEBIAN tested

Script for Bash – command

Place in your .bashrc of the user
be carefully : done by users rights / group rights; so by doing that with root,
output file is owned by root/root

so it makes sense to write chkpng in root/.bashrc
and
write fixpng only in /home/user/.bashrc

function fixpng() {
    for png in find $1 -name "*.png";
        do
            echo "crushing $png"
            pngcrush -rem sbit "$png" tmp.png
            mv -f tmp.png $png
        done;
}


function chkpng() {
    for png in find $1 -name "*.png";
        do
        #    echo "checking $png"
            pngcheck -q "$png"
        done;
}

PNGCRUSH a Directory of Images

The Bash Script

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Discussion