Converting to TIFF for "Imaging for Windows", we've encountered compatibility problems outputting paletted images from the Q16 executable. The symptom was incorrect colors being displayed in "Imaging for Windows". We were unable to solve with Q16, however finally found that output from the Q8 version were readable OK.
ImageMagick 6.8.7-6 Windows
We had tried "-depth 8" or "-define quantum:format=unsigned", but apparently the TIFF palette output from Q16 is still incompatible & may still be being saved with a higher color-precision or greater bit-depth than "Imaging for Windows" (or other older TIFF clients) can read correctly. See dump below.
This raises a couple of issues re. TIFF compatibility:
1) Palette output should be restricted to 8-bit-primary format, if depth <= 8
2) Q16 version output -> identify does not respect or keep -depth option effectively; channel depths show up always as 16-bit
Q8 version output -> identify is better; channel depths are kept & reported back correctly.
3) Are there any other options/ defines which could help to increase TIFF compatibility?
And, regarding "Identify" clarity:
4) Sometimes it is less than clear what is actually in the file, versus what "canonical format" Identify has decoded into.
- for example, "type: Palette with Base type: True color". This seems confusing, since what we wanted to know was what was in the actual file.
- unclear, but reported color-depths were unclear whether they were "as decoded" or "actual ".
Generally, we wanted to know *actual* values direct from the file, first & foremost. For sure the decoded/synthetic values are useful but I felt it was really important, especially with this kind of compatability issue, to be able to get clear direct info on the file header & encoding.
Thanks for a great software & I hope this helps ongoing improvement!
"Identify" dump of incompatible paletted output from Q16:
Code: Select all
Image: broken-pal8.tif
Format: TIFF (Tagged Image File Format)
Mime type: image/tiff
Class: PseudoClass
Geometry: 1653x2339+0+0
Resolution: 200x200
Print size: 8.265x11.695
Units: Undefined
Type: Palette
Base type: Palette
Endianess: MSB
Colorspace: sRGB
Depth: 16-bit
Channel depth:
red: 16-bit
green: 16-bit
blue: 16-bit
Channel statistics:
Red:
min: 343 (0.00523384)
max: 65508 (0.999588)
mean: 62372 (0.951736)
standard deviation: 11820.3 (0.180366)
kurtosis: 16.4096
skewness: -4.14938
Green:
min: 375 (0.00572213)
max: 65513 (0.999664)
mean: 62396.3 (0.952106)
standard deviation: 11764 (0.179507)
kurtosis: 16.5325
skewness: -4.16089
Blue:
min: 371 (0.0056611)
max: 65511 (0.999634)
mean: 62400.5 (0.952171)
standard deviation: 11759.5 (0.179439)
kurtosis: 16.5571
skewness: -4.16385
Image statistics:
Overall:
min: 343 (0.00523384)
max: 65513 (0.999664)
mean: 62389.6 (0.952004)
standard deviation: 11781.3 (0.179771)
kurtosis: 16.4997
skewness: -4.15804
Colors: 221
Histogram:
44184: ( 343, 375, 371) #015701770173 srgb(0.523384%,0.572213%,0.56611%)
305: ( 1164, 1590, 2173) #048C0636087D srgb(1.77615%,2.42618%,3.31579%)
5389: ( 1201, 2097, 1761) #04B1083106E1 srgb(1.83261%,3.19982%,2.68711%)
223: ( 1439, 2566, 2431) #059F0A06097F srgb(2.19577%,3.91547%,3.70947%)
[... snipped ...]
Colormap entries: 256
Colormap:
0: ( 343, 375, 371) #015701770173 srgb(0.523384%,0.572213%,0.56611%)
1: ( 1201, 2097, 1761) #04B1083106E1 srgb(1.83261%,3.19982%,2.68711%)
2: ( 1164, 1590, 2173) #048C0636087D srgb(1.77615%,2.42618%,3.31579%)
3: ( 1439, 2566, 2431) #059F0A06097F srgb(2.19577%,3.91547%,3.70947%)
[... snipped ...]
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)
Background color: white
Border color: srgb(223,223,223)
Matte color: grey74
Transparent color: black
Interlace: None
Intensity: Undefined
Compose: Over
Page geometry: 1653x2339+0+0
Dispose: Undefined
Iterations: 0
Compression: LZW
Orientation: TopLeft
Properties:
date:create: 2013-11-19T16:47:09+13:00
date:modify: 2013-11-19T16:44:08+13:00
signature: 0d9e5ca67bee2a901cd4291cfef5d78f139523c3cfcf30968b9c2d14d123496a
tiff:document: test-pal8.tif
tiff:endian: lsb
tiff:photometric: palette
tiff:rows-per-strip: 4
Artifacts:
filename: broken-pal8.tif
verbose: true
Tainted: False
Filesize: 608KB
Number pixels: 3.866M
Pixels per second: 87.87MB
User time: 0.047u
Elapsed time: 0:01.043
Version: ImageMagick 6.8.7-6 Q16 x86 2013-11-07 http://www.imagemagick.org