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ImageMagick convert TIF to b&w - result blank image
Posted: 2011-02-05T05:13:00-07:00
by olos
Hello,
I have two tif-s that are scans from Zeutschel Omniscan 12 and saved via Adobe Photoshop CS5 Windows. This 2 files (links below) are very similar (the same process of scanning and saving) but one s1001.tif converts to black and white with no problems using -type bilevel option. The second one s1002.tif always became blank after conversion
I tried converting this file using XnView and there is no problem. Converting image to png using convert exe and then converting to b&w using -type bilevel give the same results - blank image.
I found script in one of the thread which is combination of options like
-type bilevel -type grayscale -type optimize etc. (63 combinations) but only grayscale conversion is ok.
Can you give me a hint what is the difference between this two images that cause this behavior ?
ImageMagick versions tested
Windows XP 6.3.3 Q16 - image s1002 after conversion is all black
Windows 7 6.6.6-10 Q16 - image s1002 after conversion is all white
Tested images (about 20MB each)
http://www.webdysk.net/s1001.tif
http://www.webdysk.net/s1002.tif
test script
http://www.webdysk.net/convert.txt
Thanks in advance for help
Regards
Tom
Re: ImageMagick convert TIF to b&w - result blank image
Posted: 2011-02-05T11:10:39-07:00
by fmw42
I get an error message on IM 6.6.7.4 Q16 Mac OSX Tiger
convert s1002.tif -type bilevel s1002_bl.tif
convert: s1002.tif: wrong data type 7 for "RichTIFFIPTC"; tag ignored. `TIFFReadDirectory' @ warning/tiff.c/TIFFWarnings/706.
Looks like your tiffs are corrupt in some way.
The result is all white but the type is bilevel
identify -verbose s1002_bl.tif
Image: s1002_bl.tif
Format: TIFF (Tagged Image File Format)
Class: DirectClass
Geometry: 2405x2947+0+0
Resolution: 300x300
Print size: 8.01667x9.82333
Units: PixelsPerInch
Type: Bilevel
Base type: Bilevel
Endianess: MSB
Colorspace: RGB
Depth: 1-bit
Channel depth:
gray: 1-bit
Channel statistics:
Gray:
min: 1 (1)
max: 1 (1)
mean: 1 (1)
standard deviation: nan (nan)
kurtosis: nan
skewness: nan
Histogram:
7087535: (255,255,255) #FFFFFF white
Re: ImageMagick convert TIF to b&w - result blank image
Posted: 2011-02-06T04:15:12-07:00
by olos
Hello,
Thanks for replay.
fmw42 wrote:I get an error message on IM 6.6.7.4 Q16 Mac OSX Tiger
convert: s1002.tif: wrong data type 7 for "RichTIFFIPTC"; tag ignored. `TIFFReadDirectory' @ warning/tiff.c/TIFFWarnings/706.
This error is well known exception which is thrown by the libTIFF. IPTC profile generated by Photoshop CS4 or CS5 software is not processed well by libTIFF. The question is if this have influence on conversion to b&v. Evan if I save this image via XnView to "proper" tif or png result after convert will be the same (white page). Strange…
I've generated (using identify tool) report for both files and compared them and the main difference is in Channel statistics section. Maybe this is the source of problem. But i have no such a deep knowledge of image processing to find the solution...
Thanks for help
Regards
Tom
PS. below identify results for both files
Code: Select all
identify.exe -verbose s1001.tif
Image: s1001.tif
Format: TIFF (Tagged Image File Format)
Class: DirectClass
Geometry: 2220x2947+0+0
Type: TrueColor
Endianess: MSB
Colorspace: RGB
Channel depth:
Red: 8-bit
Green: 8-bit
Blue: 8-bit
Channel statistics:
Red:
Min: 0 (0)
Max: 255 (1)
Mean: 204.21 (0.800822)
Standard deviation: 45.9655 (0.180257)
Green:
Min: 0 (0)
Max: 255 (1)
Mean: 185.63 (0.727961)
Standard deviation: 44.9793 (0.176389)
Blue:
Min: 0 (0)
Max: 255 (1)
Mean: 161.644 (0.633897)
Standard deviation: 40.5163 (0.158887)
Colors: 459023
Rendering intent: Undefined
Resolution: 300x300
Units: PixelsPerInch
Filesize: 19.3765mb
Interlace: None
Background color: white
Border color: rgb(223,223,223)
Matte color: grey74
Transparent color: black
Page geometry: 2220x2947+0+0
Dispose: Undefined
Iterations: 0
Compression: None
Orientation: TopLeft
Artist: Zeutschel Omniscan 12
Signature: d04021f1c7cc9a09231fd0b9cedfdb8d4b447abacf9641699c630c0dd22b01fd
Software: Adobe Photoshop CS5 Windows
Timestamp: 2011:01:28 12:42:40
Profile-8bim: 6984 bytes
Code: Select all
identify.exe -verbose s1002.tif
Image: s1002.tif
Format: TIFF (Tagged Image File Format)
Class: DirectClass
Geometry: 2405x2947+0+0
Type: TrueColor
Endianess: MSB
Colorspace: RGB
Channel depth:
Red: 8-bit
Green: 8-bit
Blue: 8-bit
Channel statistics:
Red:
Min: 0 (0)
Max: 255 (1)
Mean: 201.86 (0.791608)
Standard deviation: 42.8434 (0.168014)
Green:
Min: 0 (0)
Max: 255 (1)
Mean: 179.257 (0.702969)
Standard deviation: 42.5225 (0.166755)
Blue:
Min: 0 (0)
Max: 255 (1)
Mean: 152.466 (0.597906)
Standard deviation: 36.8363 (0.144456)
Colors: 469110
Rendering intent: Undefined
Resolution: 300x300
Units: PixelsPerInch
Filesize: 20.9372mb
Interlace: None
Background color: white
Border color: rgb(223,223,223)
Matte color: grey74
Transparent color: black
Page geometry: 2405x2947+0+0
Dispose: Undefined
Iterations: 0
Compression: None
Orientation: TopLeft
Artist: Zeutschel Omniscan 12
Signature: 3f0b6a4f48cec9cc4507a4e1fb2cbd13bc43bbd64204328f390f09a541144eed
Software: Adobe Photoshop CS5 Windows
Timestamp: 2011:01:28 12:48:43
Profile-8bim: 7844 bytes
Re: ImageMagick convert TIF to b&w - result blank image
Posted: 2011-02-06T11:49:54-07:00
by fmw42
My result was type bilevel but the resulting image was all white. I think your image statistics are such that you need to specify a unique threshold level. Try
convert s1002.tif -threshold 50% s1002_t50.tif
The results in showing most of the text as black on white background and is type bilevel.
Alternately, try using -lat (local area thresholding)
Re: ImageMagick convert TIF to b&w - result blank image
Posted: 2011-02-14T01:51:38-07:00
by olos
Thank you very much for help
This combination
Code: Select all
convert s1002.tif -threshold 50% s1002_t50.tif
is the solution. I tested more than 1000 tiff-s (about 30GB) with different threshold value and there is no problem (threshold set to 56 - 60% give best results for my images).
Once again thanks for help.
Regards
Tom