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  • Re: Apple's newer image formats

    From Lawrence =?iso-8859-13?q?D=FFOliveiro?=@ldo@nz.invalid to comp.os.linux.advocacy,comp.os.ms-windows.advocacy,comp.sys.mac.advocacy on Sat Mar 14 22:03:00 2026
    From Newsgroup: comp.sys.mac.advocacy

    On Sat, 14 Mar 2026 18:16:50 +0800, Mr. Man-wai Chang wrote:

    Come on, all raw (un-compressed) formats are better than JPEG
    because JPEG and MP3 compresses using Fourier Transform!!

    Regular JPEG uses DCT. And oddly enough, so does Apple’s “ProRes” for capturing supposedly “professional”-quality raw video. This is
    well-known to suffer from blockiness artifacts if you push the
    compression too far.

    This is why JPEG2000 uses wavelet compression instead. If you push
    things too far, the image gets soft rather than blocky, which is
    considered less objectionable in terms of artifacts.
    --- Synchronet 3.21d-Linux NewsLink 1.2
  • From Lawrence =?iso-8859-13?q?D=FFOliveiro?=@ldo@nz.invalid to comp.os.linux.advocacy,comp.sys.mac.advocacy,comp.os.ms-windows.advocacy on Sat Mar 14 22:14:48 2026
    From Newsgroup: comp.sys.mac.advocacy

    On Sat, 14 Mar 2026 11:50:02 -0400, Paul wrote:

    This morning and the HEIC versus JPG experiment, I tried to get
    Irfanview working. I installed the EXE, the PLUGINS kit, and the
    CopyTrans CODEC, but Irfanview refused to decode the content.

    Did you try ImageMagick? That seems to be the closest thing to a
    universal image-format convertor/manipulator on any platform.
    --- Synchronet 3.21d-Linux NewsLink 1.2
  • From Lawrence =?iso-8859-13?q?D=FFOliveiro?=@ldo@nz.invalid to comp.os.linux.advocacy,comp.os.ms-windows.advocacy,comp.sys.mac.advocacy on Sat Mar 14 22:16:44 2026
    From Newsgroup: comp.sys.mac.advocacy

    On Sat, 14 Mar 2026 21:09:44 -0000 (UTC), Lars Poulsen wrote:

    HEIC is not uncompressed. But HEIC files are still only half the
    size of the same image in a JPG file, despite usually having more
    bits per pixel (i.e. higher dynamic range).

    PNG already supports up to 16 bits per pixel component.

    If you want 32/64-bit floating point, there is OpenEXR, already widely
    used in the DCC industry. GIMP can handle it natively at full quality,
    unlike Photoshop, which requires a quality-losing import plugin.
    --- Synchronet 3.21d-Linux NewsLink 1.2
  • From Lawrence =?iso-8859-13?q?D=FFOliveiro?=@ldo@nz.invalid to comp.os.linux.advocacy,comp.os.ms-windows.advocacy,comp.sys.mac.advocacy on Sat Mar 14 22:24:23 2026
    From Newsgroup: comp.sys.mac.advocacy

    On Sat, 14 Mar 2026 13:00:55 -0400, Paul wrote:

    https://www.imaging.org/IST/IST/Resources/Tutorials/Inside_JPEG.aspx

    What is Inside a JPEG File

    "... The DCT coefficients are computed for each 8x8 block of
    pixels in the image. To this point, the entire JPEG process is
    completely reversible except for the losses due to subsampling
    of the two chrominance channels."

    As an example the sort of thing you get in professional-quality tools,
    I just pulled up the JPEG export dialog in GIMP, and besides the usual percentage-quality setting, it allows me to choose the chrominance
    subsampling setting: this can be 4:4:4, 4:2:2, or 4:2:0.

    4:4:4 is effectively no subsampling at all.

    And there’s a choice of 3 different DCT computation methods.
    --- Synchronet 3.21d-Linux NewsLink 1.2