This archive contains a command line tool (colortransf v. 1.1) for performing 
reversible and irreversible color space transformations, including established standard 
transformations as well as new ones.  Reversible color space transformations are described in: R. Starosolski, New simple and efficient color space transformations for lossless image compression, Journal of Visual Communication and Image Representation, 2014, Vol. 25(5), pp. 1056-63, http://dx.doi.org/10.1016/j.jvcir.2014.03.003. Irreversible transformations are described in: R. Starosolski, Human Visual System Inspired Color Space Transform in Lossy JPEG 2000 and JPEG XR Compression, submitted.


This archive contains files:
readme.txt 	- this file
colortransf.cpp - a C++ source file of the colortransf tool
colortransf.exe - Win32 executable


Further description (the same will be outputted by the tool invoked with no arguments):


colortransf v. 1.1, (c) 2014, 2016 Roman Starosolski, rstarosolski@polsl.pl 
	
Apply color space transformation to RGB image obtaining transformed components, or recreate the RGB image from components using inverse transformation.
Reversible color space transformations are described in: R. Starosolski, New simple and efficient color space transformations for lossless image compression, Journal of Visual Communication and Image Representation, 2014, Vol. 25(5), pp. 1056-63, http://dx.doi.org/10.1016/j.jvcir.2014.03.003.
Irreversible transformations are described in: R. Starosolski, Human Visual System Inspired Color Space Transform in Lossy JPEG 2000 and JPEG XR Compression, submitted.
Image formats: PPM P6 (for RGB image), PGM P5 (for components), PPM plane order RGB assumed, untransformed and transformed intensities assumed unsigned.
	
This software is intended for research purposes only; it is provided "as is"; author makes no warranty of any kind, either express or implied, with respect to this software.
This work was partially supported by the POIG.02.03.01-24-099/13 grant: GeCONiI - Upper-Silesian Center for Scientific Computations.

syntax: colortransf [switches] command

 commands: 
  S infilergb.ppm redT.pgm greenT.pgm blueT.pgm  
    // split image into components, apply (optional) transformation
  U redT.pgm greenT.pgm blueT.pgm outfilergb.ppm 
    // unsplit
  TEST_TRANSF range  
    // test forward & inverse rebersible transformation for all 
    // possible combinations of component values in given range 
    // checking dynamic ranges of components and reversibility
  TEST_IRREV range  
    // test forward & inverse irreversible transformation for all 
    // possible combinations of component values in given range 
    // checking component depth violations and forward/inverse 
    // transformation errors
  
 switches: 
  [-TRANSF nr]  
    // apply transformation number nr (numbers listed below), for a detailed
    // description of transformations and components' formulas see the above
    // mentioned paper
    //
    // reversible transformations with inverses (* - 1-bit expansion):
    //  0  - RGB  (no transformation, default), 
    //       components outputted in a following order: R G B          
    //  1  - RCT (from JPEG2000 standard),          
    //       components outputted in a following order: Cv* Y Cu*      
    // -1  - inverse RCT
    //  2  - YCoCg-R (from JPEG-XR standard),       
    //       components outputted in a following order: Co* Y Cg*      
    // -2  - inverse YCoCg-R
    //  3  - RDgDb,                                 
    //       components outputted in a following order: R Dg* Db*      
    // -3  - inverse RDgDb
    //  4  - A2,                                    
    //       components outputted in a following order: VA2* YA2 UA2*  
    // -4  - inverse A2
    //  5  - LDgEb,                                 
    //       components outputted in a following order: L Dg* Eb*      
    // -5  - inverse LDgEb
    //  6  - LDgDb,                                 
    //       components outputted in a following order: L Dg* Db*      
    // -6  - inverse LDgDb
    //  7  - mRCT (from extended JPEG-LS standard), 
    //       components outputted in a following order: mCv mY mCu     
    // -7  - inverse mRCT
    //  8  - mRDgDb,                                
    //       components outputted in a following order: R mDg mDb      
    // -8  - inverse mRDgDb
    //  9  - mA2,                                   
    //       components outputted in a following order: mVA2 mYA2 mUA2 
    // -9  - inverse mA2
    //  10 - mLDgEb,                                
    //       components outputted in a following order: mL mDg mEb     
    // -10 - inverse mLDgEb
    //  11 - mLDgDb,                                
    //       components outputted in a following order: mL mDg mDb     
    // -11 - inverse mLDgDb
    //
    // for testing components' formulas (no inverse, * - 1-bit expansion):
    //  20 - ADDAVG, components outputted in a following order:   
    //                           ((2r+g+b)/4) ((2g+b+r)/4) ((2b+r+g)/4)
    //  21 - SUB, components outputted in a following order:   
    //                           (r-g)* (g-b)* (b-r)*
    //  22 - INVSUB, components outputted in a following order:   
    //                           (g-r)* (b-g)* (r-b)*
    //  23 - ADDHALF, components outputted in a following order:   
    //                           (r+g)/2 (g+b)/2 (b+r)/2
    //  24 - SUBAVG, components outputted in a following order:   
    //                           ((2r-g-b)/2)* ((2g-b-r)/2)* ((2b-r-g)/2*)
    //
    // irreversible transformations with inverses
    //  30 - ICT (from JPEG2000 standard)
    //       components outputted in a following order: Y Cr Cb   
    // -30 - inverse ICT
    //  31 - YCoCg (irreversible variant of YCoCg-R from JPEG-XR standard)
    //       components outputted in a following order: Y Co Cg   
    // -31 - inverse YCoCg
    //  32 - HVSCT (irreversible variant of LDgEb) 
    //       components outputted in a following order: Y Cd Ce   
    // -32 - inverse HVSCT
    //
  [-O_RAW] 
    // output as RAW (skip PGM/PPM header)
  [-NO_INV_CHECK] 
    // skip checking inverse transformation (or reversibility), default is to
    // check for each pixel before outputting it (S and U commands); for the 
    // TEST_TRANSF command check ranges only (skip reversibility check)
  [-U_FORCE_CLIP] 
    // clip inverse transformed components (for all transformations, done in
    // U command), use after lossy compression of transformed components;
    // default: do not clip
  [-NO_IRREV_CLIP] 
    // for irreversible transforms only: skip clipping of transformed 
    // components; default: clip

examples: 
  Split lena.ppm RGB color image into red green and blue components, saved as
  grayscale images R.ppm G.ppm B.ppm:
      colortransf S lena.ppm R.pgm G.pgm B.pgm
  Transform lena.ppm using YCoCg-R transformation, save resulting components
  as Co.ppm Y.ppm Cg.ppm:
      colortransf -TRANSF 2 S lena.ppm Co.pgm Y.pgm Cg.pgm  
  Apply inverse YCoCg-R transformation on Co.pgm Y.pgm Cg.pgm components, save
  resulting image as lena2.ppm:
      colortransf -TRANSF -2 U Co.ppm Y.pgm Cg.pgm lena2.ppm 
  Convert lena.ppm RGB color image to BRG space and apply mRCT transformation
  on image with permuted components:
      colortransf S lena.ppm R.pgm G.pgm B.pgm 
      colortransf U B.pgm R.pgm G.pgm lenaBRG.ppm 
      colortransf -TRANSF 7 S lenaBRG.ppm mCvBRG.pgm mYBRG.pgm mCuBRG.pgm  
  Transform lena.ppm using irreversible ICT transformation, save resulting 
  components as iY.ppm iCr.ppm iCb.ppm:
      colortransf -TRANSF 30 -NO_INV_CHECK S lena.ppm iY.pgm iCr.pgm iCb.pgm  
  Generate components being primary color differences (irreversible 
  operation):
      colortransf -TRANSF 21 -NO_INV_CHECK S lena.ppm R-G.pgm G-B.pgm B-R.pgm
  What errors are introduced due to forward and inverse irreversible 
  ICT transformation, for component values in 0..255 range?
      colortransf -TRANSF 30 TEST_IRREV 256
  Is mLDgEb really reversible for all possible combinations of component 
  values in 0..255 range?
      colortransf -TRANSF 10 TEST_TRANSF 256