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Full Discussion: Compression (gzip) for image analysis
Special Forums UNIX and Linux Applications Compression (gzip) for image analysis Post 302591427 by Corona688 on Thursday 19th of January 2012 12:25:23 PM
Old 01-19-2012
gzip isn't suitable. gzip wouldn't know which bits mean what pixels. gzip might also find patterns you don't want, identical things in the wrong places of the image. It's also lossless, so an intensity difference of 1 matters just as much as an intensity difference of 255 as far as it's concerned. It really doesn't know what the picture looks like.

This paper can't have meant lossless compression, or any kind of general compression -- it must have meant some kind of lossy image compression like jpg which doesn't care if the pixels are bit-for-bit identical.

I don't think 'cat' is an appropriate way to combine the images, either.

I think what they're looking for is the resulting size of the image when saved with identical levels of lossy compression. S(I1) and S(I2) should be very similar. What S(I3) is would depend. How does the paper say to combine these images?
 

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LEARN ABOUT PHP

pal2rgb

pal2rgb(1)							   User Commands							pal2rgb(1)

NAME

       pal2rgb - convert a palette color TIFF image to a full color image

SYNOPSIS

       pal2rgb [options] input.tif output.tif

DESCRIPTION

       pal2rgb	converts a palette color TIFF image to a full color image by applying the colormap of the palette image to each sample to generate
       a full color RGB image.

OPTIONS

   Input Data Options
       The following input data options are supported:

       -C	       Override the default behavior of pal2rgb to determine whether or not colormap entries contain 16-bit or	8-bit  values.	By
		       default, the colormap is inspected and if no colormap entry greater than 255 is found, the colormap is assumed to have only
		       8-bit values. Otherwise, 16-bit values, as required by the TIFF specification, are assumed. The -C option can  be  used	to
		       explicitly specify the number of bits for colormap entries: -C 8 for 8-bit values, -C 16 for 16-bit values.

   Output File Options
       The following output file options are supported:

       -c	       Specify a compression scheme to use when writing image data:

		       -c lzw		       Lempel-Ziv and Welch algorithm.

		       -c none		       No compression.

		       -c packbits	       PackBits compression algorithm.

		       -c zip		       Deflate compression algorithm.

		       If no compression-related option is specified, the input-file compression algorithm is used.

       -p	       Explicitly select the planar configuration used to organize data samples in the output image:

		       -p contig	       Samples are packed contiguously. This is the default.

		       -p separate	       Samples are stored separately.

       -r	       Write  data  with  a  specified number of rows per strip. By default, the number of rows per strip is selected so that each
		       strip is approximately 8 kilobytes.

OPERANDS

       The following operands are supported:

       input.tif       The name of the input TIFF file.

       output.tif      The name of the output file.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWTiff			   |
       +-----------------------------+-----------------------------+
       |Interface stability	     |External			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       tiffinfo(1), tiffcp(1), tiffmedian(1), libtiff(3)

NOTES

       Only 8-bit images are supported.

       Updated by Breda McColgan, Sun Microsystems Inc., 2004.

SunOS 5.10							    26 Mar 2004 							pal2rgb(1)
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