| Re: TIFF Read/Write Bug? [message #84242] |
Sun, 12 May 2013 07:08 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Tom Grydeland writes:
> The description of palette images is in section 5. For palette images, the number of bits per sample can be 4 or 8, corresponding to 16 or 256 colors (the color values are short integers, however, giving 65536 levels for each of red, blue and green at each index). For more colors than that, you must go to one of the RGB full color modes.
Yes, I think my mistake was treating TIFF images as if they were netCDF
or HDF files. I had classified data in the byte range, but I wanted to
store "missing" data with the value -999, which was why I was using an
integer array. At the same time, I didn't want to lose the color vectors
that "explained" the data.
Of course, when you store "color" images in TIFF files, it is difficult,
if not impossible, to retrieve the science information. What I should
have used, of course, is a netCDF file where I can store the palette
information separately from the data itself. Unfortunately, netCDF files
are just much more difficult for my client to handle as she likes.
There are ways to work around the "problem", but some documenation that
the problem exists, in a location where I was likely to read it, would
have helped. :-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
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| Re: TIFF Read/Write Bug? [message #84243 is a reply to message #84242] |
Sun, 12 May 2013 04:03  |
tom.grydeland
Messages: 51
Registered: September 2012
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Member |
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On Saturday, May 11, 2013 1:04:38 AM UTC+2, Heinz Stege wrote:
> I don't know the TIFF standard.
The TIFF standard is here:
http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf
The description of palette images is in section 5. For palette images, the number of bits per sample can be 4 or 8, corresponding to 16 or 256 colors (the color values are short integers, however, giving 65536 levels for each of red, blue and green at each index). For more colors than that, you must go to one of the RGB full color modes.
> [...] So it does not make any sense
> for testImage to be integer instead of byte.
Exactly.
> Cheers, Heinz
--T
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| Re: TIFF Read/Write Bug? [message #84249 is a reply to message #84243] |
Fri, 10 May 2013 16:04 |
Heinz Stege
Messages: 189
Registered: January 2003
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Senior Member |
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On Fri, 10 May 2013 14:29:16 -0700 (PDT), Phillip Bitzer wrote:
> I similar behavior David. Integer array in, integer array out .. unless the color vectors are included. Then it's byte out.
>
Same here. !version={ x86 Win32 Windows Microsoft Windows 8.0.1 Oct 5
2010 32 64}.
However, I wonder if it makes any sense to write integer arrays in
TIFF files with color palettes. I don't know the TIFF standard. But
the IDL manual for the Red, Green and Blue keywords says: "If you are
writing a Palette color image, set these keywords equal to the color
table vectors, scaled from 0 to 255."
My understanding is, that a TIFF file written by
Write_Tiff, outFilename, Reverse(ageImage,2), GEOTIFF=geo, $
/SHORT, /SIGNED, RED=r, GREEN=g, BLUE=b
has to be read by
testImage = Read_Tiff(outfilename,r,g,b)
And the pixel color values can be calculated by
red=r[testImage]
green=g[testImage]
blue=b[testImage]
r, g and b have 256 elements maximum. So it does not make any sense
for testImage to be integer instead of byte.
Cheers, Heinz
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| Re: TIFF Read/Write Bug? [message #84251 is a reply to message #84249] |
Fri, 10 May 2013 14:29 |
Phillip Bitzer
Messages: 223
Registered: June 2006
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Senior Member |
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I similar behavior David. Integer array in, integer array out .. unless the color vectors are included. Then it's byte out.
IDL> help, !version
** Structure !VERSION, 8 tags, length=104, data length=100:
ARCH STRING 'x86_64'
OS STRING 'darwin'
OS_FAMILY STRING 'unix'
OS_NAME STRING 'Mac OS X'
RELEASE STRING '8.2.2'
BUILD_DATE STRING 'Jan 23 2013'
MEMORY_BITS INT 64
FILE_OFFSET_BITS
INT 64
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| Re: TIFF Read/Write Bug? [message #84252 is a reply to message #84251] |
Fri, 10 May 2013 14:08 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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David Fanning writes:
> If I add color vectors to the file, watch this:
>
> ;*********************************************
> outFilename = 'forest.tif'
> ageimage = read_tiff(file_which('boulder.tif'))
> ageImage = Fix(ageImage)
> Help, ageImage
> dims = SIZE(ageimage, /DIMENSIONS)
> missingIndices = long(randomu(seed, 1000) * product(dims))
> ageImage[missingIndices]=-999
> TVLCT, r, g, b, /GET
> Write_Tiff, outFilename, Reverse(ageImage,2), GEOTIFF=geo, $
> /SHORT, /SIGNED, RED=r, GREEN=g, BLUE=b
> testImage = Read_Tiff(outfilename)
> testimage = Reverse(testimage,2)
> Help, testImage
> END
> ;*********************************************
>
> AGEIMAGE INT = Array[1071, 1390]
> TESTIMAGE BYTE = Array[1071, 1390]
>
> Is that weird, or what!?
For me, at least, it doesn't matter what kind of data I put into the
TIFF file (I've tried SHORT, LONG, FLOAT, and DOUBLE), if I add color
vectors, then I can ONLY get BYTE data back from the file.
Again, Windows 64-bit and IDL 8.2.2.
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
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| Re: TIFF Read/Write Bug? [message #84253 is a reply to message #84252] |
Fri, 10 May 2013 13:48 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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David Fanning writes:
> Is there a problem writing signed integer arrays to TIFF files?
>
> Here is my code:
>
> outFilename = Filepath('forest.tif')
> ageImage = Fix(ageImage)
> Help, ageImage
> AGEIMAGE INT = Array[8600, 8407]
> ageImage[missingIndices]=-999
> Write_Tiff, outFilename, Reverse(ageImage,2), /SHORT, /SIGNED
> testImage = Read_Tiff(outfilename)
> testimage = Reverse(testimage,2)
> Help, testImage
> TESTIMAGE BYTE = Array[8600, 8407]
>
> This is IDL 8.2.2, 64-bit, on Windows 7. '
Whoa! I left this out of my example the other day because it seemed (at
the time) completely irrelevant.
Here is test code that works perfectly:
;*********************************************
outFilename = 'forest.tif'
ageimage = read_tiff(file_which('boulder.tif'))
ageImage = Fix(ageImage)
Help, ageImage
dims = SIZE(ageimage, /DIMENSIONS)
missingIndices = long(randomu(seed, 1000) * product(dims))
ageImage[missingIndices]=-999
Write_Tiff, outFilename, Reverse(ageImage,2), GEOTIFF=geo, $
/SHORT, /SIGNED
testImage = Read_Tiff(outfilename)
testimage = Reverse(testimage,2)
Help, testImage
END
;*********************************************
Running it gives me:
AGEIMAGE INT = Array[1071, 1390]
TESTIMAGE INT = Array[1071, 1390]
BUT!!!
If I add color vectors to the file, watch this:
;*********************************************
outFilename = 'forest.tif'
ageimage = read_tiff(file_which('boulder.tif'))
ageImage = Fix(ageImage)
Help, ageImage
dims = SIZE(ageimage, /DIMENSIONS)
missingIndices = long(randomu(seed, 1000) * product(dims))
ageImage[missingIndices]=-999
TVLCT, r, g, b, /GET
Write_Tiff, outFilename, Reverse(ageImage,2), GEOTIFF=geo, $
/SHORT, /SIGNED, RED=r, GREEN=g, BLUE=b
testImage = Read_Tiff(outfilename)
testimage = Reverse(testimage,2)
Help, testImage
END
;*********************************************
AGEIMAGE INT = Array[1071, 1390]
TESTIMAGE BYTE = Array[1071, 1390]
Is that weird, or what!?
Can anyone reproduce this on their machines?
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
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| Re: TIFF Read/Write Bug? [message #84274 is a reply to message #84273] |
Wed, 08 May 2013 15:19 |
Heinz Stege
Messages: 189
Registered: January 2003
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Senior Member |
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Hi David,
below is the result from my IDL 8.0.1, 32 bit, WinXP. No error.
IDL> fn='F:\scans\Yms0001raw.tif'
IDL> b=read_tiff(fn)
% Loaded DLM: TIFF.
IDL> help,b
B UINT = Array[4, 4704, 6992]
IDL> b=fix(b)
IDL> b=reform(b[1,*,*])
IDL> help,b
B INT = Array[4704, 6992]
IDL> write_tiff,'test4.tif',b,/short,/signed
IDL> c=read_tiff('test4.tif')
IDL> help,c
C INT = Array[4704, 6992]
IDL> print,array_equal(b,c)
1
IDL> print,!version
{ x86 Win32 Windows Microsoft Windows 8.0.1 Oct 5 2010 32
64}
Cheers, Heinz
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