Re: CALL for DISCUSSION: eXIf 20170115

> On January 24, 2017 at 2:24 PM John Bowler <[email protected]> wrote:
> I can only conclude that Glenn hasn't
> actually implemented anything.
> 
> The issue with zpipe, on both the compress and decompress side, is
> that it *writes* the output to a *stream*.  This doesn't work because
> on both read and write the length has to be known *before* the
> operation starts.  The result of changing it to make this happen is
> more than 50 lines.

Obviously I had to work around the *stream* problem.

I'm not ready to release the code due to other pressing issues
today.  Attached is the log from an imagemagick decoding of
a "zxIf"-containing demo file
from http://www.simplesystems.org/users/glennrp/eXIf/willem

Script started on Tue 24 Jan 2017 04:13:20 PM EST
glenn.rp> pngcheck -v *zxIf.png
File: exif2c08_zxIf.png (2872 bytes)
  chunk IHDR at offset 0x0000c, length 13
    32 x 32 image, 24-bit RGB, non-interlaced
  chunk zxIf at offset 0x00025, length 623
    unknown private, ancillary, safe-to-copy chunk
  chunk IDAT at offset 0x002a0, length 2180
    zlib: deflated, 4K window, maximum compression
  chunk IEND at offset 0x00b30, length 0
No errors detected in exif2c08_zxIf.png (4 chunks, 6.5% compression).
glenn.rp> im identify -verbose -debug coder -log %e exif2c08_zxIf.png
Enter ReadPNGImage()
  Enter ReadOnePNGImage()
    IM version     = 7.0.4-5
    Libpng version = 1.2.54
    Zlib version   = 1.2.8
    Before reading:
      image->alpha_trait=0      image->rendering_intent=2
      image->colorspace=23
      image->gamma=0.454545
    read_user_chunk: found zxIf chunk
     recognized uxIf|zxIf chunk
     initialized uxIf|zxIf chunk
     chunk->data[0]=0
    PNG width: 32, height: 32
    PNG color_type: 2, bit_depth: 8
    PNG compression_method: 0
    PNG interlace_method: 0, filter_method: 0
    Setting sRGB as if in input
    image->colorspace=23
    Reading PNG IDAT chunk(s)
    Converting PNG pixels to pixel packets
    Looking for cheap transparent pixel
    No transparent pixel was found
  image->storage_class=1
  exit ReadOnePNGImage()
  page.w: 0, page.h: 0,page.x: 0, page.y: 0.
  image->colorspace: 23
exit ReadPNGImage()
Image: exif2c08_zxIf.png
  Format: PNG (Portable Network Graphics)
  Mime type: image/png
  Class: DirectClass
  Geometry: 32x32+0+0
  Resolution: 72x72
  Print size: 0.444444x0.444444
  Units: PixelsPerInch
  Type: TrueColor
  Endianess: Undefined
  Colorspace: sRGB
  Depth: 8-bit
  Channel depth:
    Red: 8-bit
    Green: 8-bit
    Blue: 8-bit
  Channel statistics:
    Pixels: 1024
    Red:
      min: 97 (0.380392)
      max: 255 (1)
      mean: 212.585 (0.833667)
      standard deviation: 45.6924 (0.179186)
      kurtosis: -0.528099
      skewness: -0.917738
      entropy: 0.863823
    Green:
      min: 184 (0.721569)
      max: 255 (1)
      mean: 235.059 (0.921798)
      standard deviation: 20.684 (0.0811136)
      kurtosis: -0.840804
      skewness: -0.729286
      entropy: 0.845184
    Blue:
      min: 66 (0.258824)
      max: 167 (0.654902)
      mean: 118.676 (0.465395)
      standard deviation: 15.3684 (0.0602683)
      kurtosis: 0.275875
      skewness: 0.0264405
      entropy: 0.919218
  Image statistics:
    Overall:
      min: 66 (0.258824)
      max: 255 (1)
      mean: 188.773 (0.740287)
      standard deviation: 30.2865 (0.11877)
      kurtosis: 16.972
      skewness: -2.00134
      entropy: 0.876075
  Colors: 958
  Histogram:
         1: ( 97,215,121) #61D779 srgb(97,215,121)
  [...]
         1: (255,255,145) #FFFF91 srgb(255,255,145)
  Rendering intent: Perceptual
  Gamma: 0.454545
  Chromaticity:
    red primary: (0.64,0.33)
    green primary: (0.3,0.6)
    blue primary: (0.15,0.06)
    white point: (0.3127,0.329)
  Alpha color: grey74
  Background color: white
  Border color: srgb(223,223,223)
  Transparent color: none
  Interlace: None
  Intensity: Undefined
  Compose: Over
  Page geometry: 32x32+0+0
  Dispose: Undefined
  Iterations: 0
  Compression: Zip
  Orientation: TopLeft
  Properties:
    date:create: 2017-01-23T23:53:44-05:00
    date:modify: 2017-01-23T23:53:44-05:00
    exif:ColorSpace: 65535
    exif:ComponentsConfiguration: 1, 2, 3, 0
    exif:Copyright: 2017 Willem van Schaik
    exif:ExifOffset: 138
    exif:ExifVersion: 48, 50, 50, 48
    exif:FlashPixVersion: 48, 49, 48, 48
    exif:Orientation: 1
    exif:ResolutionUnit: 2
    exif:thumbnail:Compression: 6
    exif:thumbnail:JPEGInterchangeFormat: 314
    exif:thumbnail:JPEGInterchangeFormatLength: 663
    exif:thumbnail:ResolutionUnit: 2
    exif:thumbnail:XResolution: 72/1
    exif:thumbnail:YResolution: 72/1
    exif:UserComment: 65, 83, 67, 73, 73, 0, 0, 0, 80, 110, 103, 83, 117, 105, 116, 101
    exif:XResolution: 72/1
    exif:YCbCrPositioning: 1
    exif:YResolution: 72/1
    png:IHDR.bit-depth-orig: 8
    png:IHDR.bit_depth: 8
    png:IHDR.color-type-orig: 2
    png:IHDR.color_type: 2 (Truecolor)
    png:IHDR.interlace_method: 0 (Not interlaced)
    png:IHDR.width,height: 32, 32
    png:sRGB: intent=0 (Perceptual Intent)
    signature: c22dc7f8430b1f787047f2dc4b77faf136ae54956ddb5912b29c1d937f5b315c
  Profiles:
    Profile-exif: 629 bytes
exif(629): 0x00000000: 78696600 004d4d00 2a000000 08000701 12000300  Exif--MM-*----------
0x00000190: 00000100 01000001 1a000500 00000100 00006201  -------------------b
0x00000320: 1b000500 00000100 00006a01 28000300 00000100  -----------j-(------
0x000004b0: 02000002 13000300 00000100 01000082 98000200  --------------------
0x00000640: 00001700 00007287 69000400 00000100 00008a00  -------r-i----------
0x000007d0: 0000dc00 00004800 00000100 00004800 00000132  -------H-------H----
0x00000960: 30313720 57696c6c 656d2076 616e2053 63686169  2017 Willem van Scha
0x00000af0: 6b000000 05900000 07000000 04303232 30910100  ik------------0220--
0x00000c80: 07000000 04010203 00928600 07000000 10000000  --------------------
0x00000e10: cca00000 07000000 04303130 30a00100 03000000  ----------0100------
0x00000fa0: 01ffff00 00000000 00415343 49490000 00506e67  ----------ASCII---Pn
0x00001130: 53756974 65000601 03000300 00000100 06000001  gSuite--------------
0x000012c0: 1a000500 00000100 00012a01 1b000500 00000100  -----------*--------
0x00001450: 00013201 28000300 00000100 02000002 01000400  ---2-(--------------
0x000015e0: 00000100 00013a02 02000400 00000100 00029700  -------:------------
0x00001770: 00000000 00004800 00000100 00004800 000001ff  -------H-------H----
0x00001900: d8ffe000 104a4649 46000101 00000100 010000ff  ------JFIF----------
0x00001a90: db004300 03020203 02020303 03030403 03040508  ---C----------------
0x00001c20: 05050404 050a0707 06080c0a 0c0c0b0a 0b0b0d0e  --------------------
0x00001db0: 12100d0e 110e0b0b 10161011 13141515 150c0f17  --------------------
0x00001f40: 18161418 12141514 ffdb0043 01030404 05040509  ------------C-------
0x000020d0: 05050914 0d0b0d14 14141414 14141414 14141414  --------------------
0x00002260: 14141414 14141414 14141414 14141414 14141414  --------------------
0x000023f0: 14141414 14141414 14141414 14141414 14ffc000  --------------------
0x00002580: 11080008 00080301 22000211 01031101 ffc4001f  ---------"----------
0x00002710: 00000105 01010101 01010000 00000000 00000102  --------------------
0x000028a0: 03040506 0708090a 0bffc400 b5100002 01030302  --------------------
0x00002a30: 04030505 04040000 017d0102 03000411 05122131  ----------}--------!
0x00002bc0: 41061351 61072271 14328191 a1082342 b1c11552  1A--Qa-"q-2----#B---
0x00002d50: d1f02433 62728209 0a161718 191a2526 2728292a  R--$3br--------%&'()
0x00002ee0: 34353637 38393a43 44454647 48494a53 54555657  *456789:CDEFGHIJSTUV
0x00003070: 58595a63 64656600 00                          WXYZcdef-
  Artifacts:
    verbose: true
  Tainted: False
  Filesize: 2.87KB
  Number pixels: 1.02K
  Pixels per second: 51.2KB
  User time: 0.000u
  Elapsed time: 0:01.019
  Version: ImageMagick 7.0.4-5 Q16 x86_64 2017-01-22 http://www.imagemagick.org
glenn.rp> pngcheck -v *xiIf_im.png File: exif2c08_zxiIf_im.png (4217 bytes)
  chunk IHDR at offset 0x0000c, length 13
    32 x 32 image, 24-bit RGB, non-interlaced
  chunk cHRM at offset 0x00025, length 32
    White x = 0.3127 y = 0.329,  Red x = 0.64 y = 0.33
    Green x = 0.3 y = 0.6,  Blue x = 0.15 y = 0.06
  chunk bKGD at offset 0x00051, length 6
    red = 0x00ff, green = 0x00ff, blue = 0x00ff
  chunk pHYs at offset 0x00063, length 9: 2834x2834 pixels/meter (72 dpi)
  chunk zTXt at offset 0x00078, length 490, keyword: Raw profile type exif
  chunk IDAT at offset 0x0026e, length 2180
    zlib: deflated, 4K window, maximum compression
  chunk exIf at offset 0x00afe, length 623
    unknown private, ancillary, safe-to-copy chunk
  chunk tEXt at offset 0x00d79, length 37, keyword: date:create
  chunk tEXt at offset 0x00daa, length 37, keyword: date:modify
  chunk tEXt at offset 0x00ddb, length 21, keyword: exif:ColorSpace
  chunk tEXt at offset 0x00dfc, length 39, keyword: exif:ComponentsConfiguration
  chunk tEXt at offset 0x00e2f, length 37, keyword: exif:Copyright
  chunk tEXt at offset 0x00e60, length 19, keyword: exif:ExifOffset
  chunk tEXt at offset 0x00e7f, length 31, keyword: exif:ExifVersion
  chunk tEXt at offset 0x00eaa, length 35, keyword: exif:FlashPixVersion
  chunk tEXt at offset 0x00ed9, length 28, keyword: exif:thumbnail:Compression
  chunk tEXt at offset 0x00f01, length 40, keyword: exif:thumbnail:JPEGInterchangeFormat
  chunk tEXt at offset 0x00f35, length 46, keyword: exif:thumbnail:JPEGInterchangeFormatLength
  chunk tEXt at offset 0x00f6f, length 31, keyword: exif:thumbnail:ResolutionUnit
  chunk tEXt at offset 0x00f9a, length 31, keyword: exif:thumbnail:XResolution
  chunk tEXt at offset 0x00fc5, length 31, keyword: exif:thumbnail:YResolution
  chunk tEXt at offset 0x00ff0, length 82, keyword: exif:UserComment
  chunk tEXt at offset 0x0104e, length 23, keyword: exif:YCbCrPositioning
  chunk IEND at offset 0x01071, length 0
No errors detected in exif2c08_zxiIf_im.png (24 chunks, -37.3% compression).
glenn.rp> exit
exit

Script done on Tue 24 Jan 2017 04:15:45 PM EST

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