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Attached image size discrepancy

FeralFeral MEMETICHARIZARDinterior crocodile alligator ⇔ ǝɹʇɐǝɥʇ ǝᴉʌoɯ ʇǝloɹʌǝɥɔ ɐ ǝʌᴉɹp ᴉRegistered User regular
This came from the following comment: https://forums.penny-arcade.com/discussion/comment/34687052/#Comment_34687052

I attached and posted a PNG image that was 424Kb png.

On my phone's file manager, it shows as 424Kb. (Android 5.1.1). In the post footer where it shows an attached image, it shows as 424k. When I sync it using Google Drive to a WIndows 7 computer, it still shows as 424kb.

bvNN6Am.jpg

However, I received feedback from other forumers that this file was over the size limit. Trace said it was 8Mb.

When I right-click on the image link in the Vanilla post, it downloads as a 7.92Mb png. The filename is different, too.

huviUYB.png

They're both 1920x1080px pngs, so I don't know what the difference is.

every person who doesn't like an acquired taste always seems to think everyone who likes it is faking it. it should be an official fallacy.
the "no true scotch man" fallacy.
Feral on

Posts

  • FeralFeral MEMETICHARIZARD interior crocodile alligator ⇔ ǝɹʇɐǝɥʇ ǝᴉʌoɯ ʇǝloɹʌǝɥɔ ɐ ǝʌᴉɹp ᴉRegistered User regular
    My gut feeling is that there's some compression algorithm in the original file that gets stripped after it's uploaded to Vanilla and attached in a post, but I have no direct evidence to support that.

    every person who doesn't like an acquired taste always seems to think everyone who likes it is faking it. it should be an official fallacy.
    the "no true scotch man" fallacy.
  • ronyaronya Arrrrrf. the ivory tower's basementRegistered User regular
    could you post a link to the image?

    aRkpc.gif
  • FeralFeral MEMETICHARIZARD interior crocodile alligator ⇔ ǝɹʇɐǝɥʇ ǝᴉʌoɯ ʇǝloɹʌǝɥɔ ɐ ǝʌᴉɹp ᴉRegistered User regular
    ronya wrote: »
    could you post a link to the image?

    http://ge.tt/6Xy6hrY2

    every person who doesn't like an acquired taste always seems to think everyone who likes it is faking it. it should be an official fallacy.
    the "no true scotch man" fallacy.
  • ronyaronya Arrrrrf. the ivory tower's basementRegistered User regular
    That's not a 424kb image or a 7.92mb image

    aRkpc.gif
  • ronyaronya Arrrrrf. the ivory tower's basementRegistered User regular
    also, your URL shortener sucks (why are you even using one)

    F2UEsw0.png

    aRkpc.gif
  • FeralFeral MEMETICHARIZARD interior crocodile alligator ⇔ ǝɹʇɐǝɥʇ ǝᴉʌoɯ ʇǝloɹʌǝɥɔ ɐ ǝʌᴉɹp ᴉRegistered User regular
    edited March 2016
    ronya wrote: »
    also, your URL shortener sucks (why are you even using one)

    time to dust off le olde NIX site I guess

    http://feral.chaosnet.org/odd/Screenshot_2016-03-14-17-27-12.png

    Feral on
    every person who doesn't like an acquired taste always seems to think everyone who likes it is faking it. it should be an official fallacy.
    the "no true scotch man" fallacy.
  • ronyaronya Arrrrrf. the ivory tower's basementRegistered User regular
    edited March 2016
    it's definitely altering the image, the bit depth changes

    ronya on
    aRkpc.gif
    FeralEnd
  • IrukaIruka Registered User, Moderator mod
    edited March 2016
    The forums use a bit of compression.

    Iruka on
  • EndEnd Registered User regular
    edited March 2016
    adding another channel shouldn't increase the image size by that much

    compression changes would though, per pngcheck:
    File: Screenshot_2016-03-14-17-27-12.png (435124 bytes)
    [...]
      chunk IDAT at offset 0x00034, length 8192
        zlib: deflated, 32K window, default compression
    [...]
    No errors detected in Screenshot_2016-03-14-17-27-12.png (57 chunks, 93.0% compression).
    
    File: xtsqxnt8e9zq.png (8309813 bytes)
    [...]
      chunk IDAT at offset 0x0003a, length 8192
        zlib: deflated, 32K window, superfast compression
    [...]
    No errors detected in xtsqxnt8e9zq.png (1016 chunks, -0.2% compression).
    

    The compression level changed from "default" to "superfast", resulting in a change from 93% compression to -0.2% compression.
    Yikes!

    End on
    I wish that someway, somehow, that I could save every one of us
    zaleiria-by-lexxy-sig.jpgsteam~tinythumb.png
    BroloFeralbowenCaulk Bite 6BahamutZEROwandering
  • BahamutZEROBahamutZERO Registered User regular
    another example, all the .png screenshots uploaded in this post are ballooning up to 8 megabytes from their original size of about 900 kilobytes:
    http://forums.penny-arcade.com/discussion/comment/34760728#Comment_34760728

    BahamutZERO.gif
  • FyreWulffFyreWulff Registered User, ClubPA regular
    edited March 2016
    Interestingly, 7.9x MB is the same exact size as a 1920x1080 32 bit .tga file with RLE off. Something's up with whatever backend saving/conversion is going on, images are being stored and served completely uncompressed.

    FyreWulff on
  • BahamutZEROBahamutZERO Registered User regular
    edited March 2016
    the ballooned files (in that thread) are 8,114.23 KB according to my browser

    BahamutZERO on
    BahamutZERO.gif
  • bowenbowen How you doin'? Registered User regular
    https://github.com/vanilla/vanilla/blob/99b6f6a3c61e9c08db5f507ccd4300b16333db1f/library/core/class.uploadimage.php

    Looks like there might be some 'processing' involved in handling image uploads if they're larger in dimensions. That might actually be stripping compression and other metadata/config/etc out of these pngs.

    I wonder if it happens with pngs that are less than 1000px wide/tall ? Not sure what the exact cut off is.

    not a doctor, not a lawyer, examples I use may not be fully researched so don't take out of context plz, don't @ me
  • IcyLiquidIcyLiquid Two Steaks Montreal, QuebecAdministrator, Vanilla Staff vanilla
    We re-encode all images that get uploaded in order to get rid of any injected exploits. We'd had trouble with larger images (20000px x 20000px) uploads causing thrashing on app servers, hence the conditional handling. I don't think stripping compression was intended.

    bowen
  • IcyLiquidIcyLiquid Two Steaks Montreal, QuebecAdministrator, Vanilla Staff vanilla
    This should now be resolved. Previously uploaded images will, regrettably, remain yuuuuuuge. Everyone says so.

    CarpyElvenshaeDonovan PuppyfuckercrimsoncoyoteFeralbowenRiusCaulk Bite 6Elldren
  • IcyLiquidIcyLiquid Two Steaks Montreal, QuebecAdministrator, Vanilla Staff vanilla
    9l5yfxj0zsdf.png

    Test

    Donovan PuppyfuckercrimsoncoyoteFeralbowenEndCaulk Bite 6wandering
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