<!-- manual page source format generated by PolyglotMan v3.2, --> <!-- available at http://polyglotman.sourceforge.net/ --> <html> <head> <title>IM_LAB_MORPH(3) manual page</title> </head> <body bgcolor='white'> <a href='#toc'>Table of Contents</a><p> <h2><a name='sect0' href='#toc0'>Name</a></h2> im_lab_morph - calculate colour differences <h2><a name='sect1' href='#toc1'>Synopsis</a></h2> #include <vips/vips.h> <p> int im_lab_morph( IMAGE *in, IMAGE *out, <br> DOUBLEMASK *mask,<br> <br> double L_offset, double L_scale,<br> <br> double a_scale, double b_scale )<br> <p> <h2><a name='sect2' href='#toc2'>Description</a></h2> This function tweaks the colour in an LAB image. It’s useful for making a ’tweaked’ image for sending to a colour printer. <p> It performs three corrections: first, it straightens the neutral axis (this is useful if your printer tends to tint shadows slightly red, for example); it moves L* by adding an offset and then multiplying by a scale (useful if your printer thinks in relative colorimetry, for example), and finally scales a* and b* by a factor (useful if your printer desaturates to avoid gamut clipping). <p> The neutral axis straightening is specified as a DOUBLEMASK containing L*, a* and b* readings taken from a print of a neutral greyscale (one with a* and b* zero). For example: <p> <tt> </tt> <tt> </tt> <tt> </tt> <tt> </tt> 3 4<br> <tt> </tt> <tt> </tt> <tt> </tt> <tt> </tt> 14.23 4.8 -3.95<br> <tt> </tt> <tt> </tt> <tt> </tt> <tt> </tt> 18.74 2.76 -2.62<br> <tt> </tt> <tt> </tt> <tt> </tt> <tt> </tt> 23.46 1.4 -1.95<br> <tt> </tt> <tt> </tt> <tt> </tt> <tt> </tt> 27.53 1.76 -2.01<br> <p> This is interpolated to make an a/b offset for each input value of L*. The top and tail are interpolated towards [100,0,0] and [0,0,0]. Entries in the mask can be in any order. <p> <h2><a name='sect3' href='#toc3'>Return Value</a></h2> All functions return 0 on success and -1 on error. <h2><a name='sect4' href='#toc4'>Copyright</a></h2> National Gallery, 2001 <p> <p> <hr><p> <a name='toc'><b>Table of Contents</b></a><p> <ul> <li><a name='toc0' href='#sect0'>Name</a></li> <li><a name='toc1' href='#sect1'>Synopsis</a></li> <li><a name='toc2' href='#sect2'>Description</a></li> <li><a name='toc3' href='#sect3'>Return Value</a></li> <li><a name='toc4' href='#sect4'>Copyright</a></li> </ul> </body> </html>