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A
ACS LLC
Inspiring
August 20, 2015
Answered

compressing PNG images

  • August 20, 2015
  • 2 replies
  • 2573 views

I have a script that captures PNG images from a 3rd party server, I then save them on my server using  this code, forcing them to 45x45

<cfimage

    action = "resize"

    height = "45"

    width  = "45"

    source = "#objImage#"

    destination = "#newFileName#"

    overwrite = "yes">

The issue I see is that the file sizes are nowhere near as low as they could be, I dropped a few of them into tinypng.com and they can be reduced by as much as 75%, and at least 50% with no noticeable loss in visual quality.

The question is, does anybody have a method to compress PNG's? I see that the quality="" is only suitable for JPGS

Btw I'm running this on CF8

    This topic has been closed for replies.
    Correct answer ACS LLC

    It looks like I have a solution.

    The good people at PNGout ( http://www.ardfry.com ) told me to check out https://pngquant.org/ which uses lossy compression, by dithering (aka quantizes) the image.


    Looking at their site it appeared that they have different ways to test their software with links to third parties who use their software, one of them being http://www.tinyPNG.org , as you'll see in my thread above I wanted to produce the same excellent results of tinypng.


    I downloaded the pngquant command line version for Windows and used CFEXECUTE to run it, it was super easy -->

    <cfexecute name = "d:\pngquant.exe"

    arguments = "d:\232.png --ext .png --force --speed 5"

    outputFile = ""

    timeout = "60">

    </cfexecute>

    In order for it not to create a new file but overwrite the original, I added --ext .png , otherwise you end up with two images

    I noticed I could get it to run around twice as fast with -- speed 5, and still get the same amazing results, dropping 20k images down to around 5k, with no obvious drop in visual quality, if you go for -- speed 11, the fastest it can be a lot quicker, but the file sizes although still much smaller are not at their smallest.

    The only argument I did have trouble with was -- skip-if-larger which is supposed to skip creation of the image if the results of the new image are actually larger than the original, however when I tried it I found that the new image would not create even though it would indeed be smaller (I've emailed them regarding this problem)

    Ardfry did suggest that I then run the image through their lossless pngout to gain further on file size reduction, the tests I did with this did help, but only by around 2% or so.

    This does appear to be a good clean solution, that is reasonably quick so I'll make this as the correct answer.

    Thanks for your input.

    2 replies

    James Moberg
    James Moberg
    Inspiring
    August 20, 2015

    GraphicsMagick has some PNG options... I wrote a custom tag to use on ColdFusion 8-11. GM supports 88 format and provides safer & faster manipulations. (It works with CMYK JPGs without compatibility or HEAP issues):
    http://gamesover2600.tumblr.com/post/125766251344/graphicsmagick-coldfusion-custom-tag

    If you use GraphicsMagick, you'll be able to tweak the optimization settings too and generate thumbnails for an entire sub-directory with a single call.

    Here's an article from SmashingMagazine regarding good compression settings for ImageMagick (similar to GraphicsMagick):
    http://www.smashingmagazine.com/2015/06/efficient-image-resizing-with-imagemagick/

    I'm also working on using ColdFusion with ExifTool. Using ImageRead() to determine if an image is CMYK has caused us a lot of performance problems. (80 seconds versus 300-500ms.)

    A
    ACS LLCAuthorCorrect answer
    Inspiring
    August 24, 2015

    It looks like I have a solution.

    The good people at PNGout ( http://www.ardfry.com ) told me to check out https://pngquant.org/ which uses lossy compression, by dithering (aka quantizes) the image.


    Looking at their site it appeared that they have different ways to test their software with links to third parties who use their software, one of them being http://www.tinyPNG.org , as you'll see in my thread above I wanted to produce the same excellent results of tinypng.


    I downloaded the pngquant command line version for Windows and used CFEXECUTE to run it, it was super easy -->

    <cfexecute name = "d:\pngquant.exe"

    arguments = "d:\232.png --ext .png --force --speed 5"

    outputFile = ""

    timeout = "60">

    </cfexecute>

    In order for it not to create a new file but overwrite the original, I added --ext .png , otherwise you end up with two images

    I noticed I could get it to run around twice as fast with -- speed 5, and still get the same amazing results, dropping 20k images down to around 5k, with no obvious drop in visual quality, if you go for -- speed 11, the fastest it can be a lot quicker, but the file sizes although still much smaller are not at their smallest.

    The only argument I did have trouble with was -- skip-if-larger which is supposed to skip creation of the image if the results of the new image are actually larger than the original, however when I tried it I found that the new image would not create even though it would indeed be smaller (I've emailed them regarding this problem)

    Ardfry did suggest that I then run the image through their lossless pngout to gain further on file size reduction, the tests I did with this did help, but only by around 2% or so.

    This does appear to be a good clean solution, that is reasonably quick so I'll make this as the correct answer.

    Thanks for your input.

    M
    mack_
    Participating Frequently
    August 20, 2015

    Try running pngout and/or pngcrush on them.

    A
    ACS LLCAuthor
    Inspiring
    August 20, 2015

    Thanks for the reply. Is pngout / pngcrush similar to tinypng, or is it a component that I can install and run using the CF code?

    M
    mack_
    Participating Frequently
    August 20, 2015

    Thanks for the reply. Is pngout / pngcrush similar to tinypng, or is it a

    component that I can install and run using the CF code?

    Both are compiled programs that you can run with CFEXECUTE from ColdFusion.

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