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unknown field with tag 37724 (0x935c) encountered. `TIFFRead

Posted: 2013-02-24T08:26:07-07:00
by Smalton8
a.tif (12.0 MB)
a.jpg (4.0 MB)
(Images are cattle grazing)

When converting a tif to jpg with:

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convert a.tif a.jpg
I get the following non-fatal error:

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a.tif: unknown field with tag 37724 (0x935c) encountered. `TIFFReadDirectory' @ warning/tiff.c/TIFFWarnings/704.
The file converts.

Tag 37724 is a Photoshop-specific TIFF Tag described as:

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tImageSourceData . Begins with the null-terminated string " Adobe Photoshop Document Data Block ", (**PSB** " Adobe Photoshop Document Data V0002 "), followed by data of various types. 
According to the photoshop TIFF spec it is the:
Adobe Photoshop specific image source data tag. This section has the layer and mask information found in a typical layered Photoshop file.
Field: ImageSourceData
Tag: 37724 (935C.H)
Type: UNDEFINED
Count: number of bytes for section
The section starts with a character string of "Adobe Photoshop Document Data Block" including the null termination character.
The remainder of the count, after subtracting the length of the above mentioned string, is a series of tagged data types in the following format:
  • 4 bytes Signature ‘8BIM’
  • 4 bytes Type various types (see below)
  • 4 bytes Length length in bytes, variable for each type, padded to a 4 byte offset
The various types are mentioned here with further documentation in the Photoshop File Formats.pdf.
The available types are:
  • ‘Layr’ Layer Data
  • ‘LMsk’ User Mask Same as Global layer mask info table
  • ‘Patt’ Pattern
  • ‘Anno’ Annotations
In cases where the tag's only information is "Adobe Photoshop Document Data Block" then it could be ignored.

Running identify also gives the non-fatal warning:

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identify: a.tif: unknown field with tag 37724 (0x935c) encountered. `TIFFReadDirectory' @ warning/tiff.c/TIFFWarnings/704.
Running "identify -verbose a.tif" gives:
Image: a.tif
Format: TIFF (Tagged Image File Format)
Class: DirectClass
Geometry: 2100x1500+0+0
Resolution: 300x300
Print size: 7x5
Units: PixelsPerInch
Type: ColorSeparation
Base type: ColorSeparation
Endianess: MSB
Colorspace: CMYK
Depth: 8-bit
Channel depth:
cyan: 8-bit
magenta: 8-bit
yellow: 8-bit
black: 8-bit
Channel statistics:
Cyan:
min: 0 (0)
max: 255 (1)
mean: 162.165 (0.63594)
standard deviation: 39.888 (0.156424)
kurtosis: 1.94603
skewness: -1.37037
Magenta:
min: 0 (0)
max: 255 (1)
mean: 113.179 (0.44384)
standard deviation: 54.0543 (0.211977)
kurtosis: -0.812667
skewness: -0.412032
Yellow:
min: 0 (0)
max: 255 (1)
mean: 160.781 (0.630514)
standard deviation: 51.0776 (0.200304)
kurtosis: 2.89463
skewness: -1.92863
Black:
min: 0 (0)
max: 228 (0.894118)
mean: 90.0339 (0.353074)
standard deviation: 70.9254 (0.278139)
kurtosis: -1.2624
skewness: 0.323196
Image statistics:
Overall:
min: 0 (0)
max: 255 (1)
mean: 105.232 (0.412674)
standard deviation: 77.2622 (0.302989)
kurtosis: -1.54447
skewness: -0.242523
Total ink density: 299%
Rendering intent: Undefined
Interlace: None
Background color: white
Border color: cmyk(223,223,223,0)
Matte color: grey74
Transparent color: black
Compose: Over
Page geometry: 2100x1500+0+0
Dispose: Undefined
Iterations: 0
Compression: None
Orientation: TopLeft
Properties:
date:create: 2013-02-24T06:44:55+04:00
date:modify: 2013-02-24T05:51:49+04:00
signature: a6fb7eebb43c66120bc230bd7b417436ba5315640908c27773f3f79a59a5c697
tiff:photometric: separated
tiff:rows-per-strip: 1
Profiles:
Profile-8bim: 6360 bytes
Profile-tiff:37724: 36 bytes
Artifacts:
verbose: true
Tainted: False
Filesize: 12.61MB
Number pixels: 3.15M
Pixels per second: 39.37M
User time: 0.090u
Elapsed time: 0:01.080
Version: ImageMagick 6.6.2-6 2012-08-17 Q16 http://www.imagemagick.org
Running "identify -verbose a.jpg" gives:
Image: a.jpg
Format: JPEG (Joint Photographic Experts Group JFIF format)
Class: DirectClass
Geometry: 2100x1500+0+0
Resolution: 300x300
Print size: 7x5
Units: PixelsPerInch
Type: ColorSeparation
Endianess: Undefined
Colorspace: CMYK
Depth: 8-bit
Channel depth:
cyan: 8-bit
magenta: 8-bit
yellow: 8-bit
black: 8-bit
Channel statistics:
Cyan:
min: 0 (0)
max: 255 (1)
mean: 162.17 (0.635961)
standard deviation: 39.8971 (0.156459)
kurtosis: 1.94155
skewness: -1.3691
Magenta:
min: 0 (0)
max: 255 (1)
mean: 113.185 (0.443864)
standard deviation: 54.0673 (0.212029)
kurtosis: -0.815962
skewness: -0.410681
Yellow:
min: 0 (0)
max: 255 (1)
mean: 160.787 (0.630539)
standard deviation: 51.1101 (0.200432)
kurtosis: 2.88207
skewness: -1.92432
Black:
min: 0 (0)
max: 229 (0.898039)
mean: 90.0631 (0.353189)
standard deviation: 70.9066 (0.278065)
kurtosis: -1.26201
skewness: 0.324144
Image statistics:
Overall:
min: 0 (0)
max: 255 (1)
mean: 105.241 (0.41271)
standard deviation: 77.2664 (0.303006)
kurtosis: -1.54434
skewness: -0.241958
Total ink density: 299%
Rendering intent: Undefined
Interlace: None
Background color: white
Border color: cmyk(223,223,223,0)
Matte color: grey74
Transparent color: black
Compose: Over
Page geometry: 2100x1500+0+0
Dispose: Undefined
Iterations: 0
Compression: JPEG
Quality: 92
Orientation: Undefined
Properties:
date:create: 2013-02-24T18:49:25+04:00
date:modify: 2013-02-24T18:49:25+04:00
jpeg:colorspace: 4
jpeg:sampling-factor: 1x1,1x1,1x1,1x1
signature: d2fdabfe6b1f77a4cd4660956d04cd4719a1e35b1ed611b90579e1582d0dce6f
Profiles:
Profile-8bim: 6360 bytes
Artifacts:
verbose: true
Tainted: False
Filesize: 4.16MB
Number pixels: 3.15M
Pixels per second: 5.943M
User time: 0.530u
Elapsed time: 0:01.530
Version: ImageMagick 6.6.2-6 2012-08-17 Q16 http://www.imagemagick.org
Version info:

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Version: ImageMagick 6.6.2-6 2012-08-17 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2010 ImageMagick Studio LLC
Features: OpenMP
 

Re: unknown field with tag 37724 (0x935c) encountered. `TIFF

Posted: 2013-02-24T10:16:17-07:00
by magick
TIFF supports proprietary tags such as 37724. When it sees a non-standard tag it reports it but silently ignores it. However ImageMagick copies it as a private blob (e.g. profile-tiff:37724). This is not a bug but expected behavior. You need to exact the data yourself from the blob or perhaps contact the libTIFF developers and suggest they support the 37724 tag in the future.