Esempio n. 1
0
/**
 * im_buildlut:
 * @input: input mask
 * @output: output image
 *
 * This operation builds a lookup table from a set of points. Intermediate
 * values are generated by piecewise linear interpolation. 
 *
 * For example, consider this 2 x 2 matrix of (x, y) coordinates:
 *
 *   <tgroup cols='2' align='left' colsep='1' rowsep='1'>
 *     <tbody>
 *       <row>
 *         <entry>0</entry>
 *         <entry>0</entry>
 *       </row>
 *       <row>
 *         <entry>255</entry>
 *         <entry>100</entry>
 *       </row>
 *     </tbody>
 *   </tgroup>
 * 
 * We then generate:
 *
 *   <tgroup cols='2' align='left' colsep='1' rowsep='1'>
 *     <thead>
 *       <row>
 *         <entry>Index</entry>
 *         <entry>Value</entry>
 *       </row>
 *     </thead>
 *     <tbody>
 *       <row>
 *         <entry>0</entry>
 *         <entry>0</entry>
 *       </row>
 *       <row>
 *         <entry>1</entry>
 *         <entry>0.4</entry>
 *       </row>
 *       <row>
 *         <entry>...</entry>
 *         <entry>etc. by linear interpolation</entry>
 *       </row>
 *       <row>
 *         <entry>255</entry>
 *         <entry>100</entry>
 *       </row>
 *     </tbody>
 *   </tgroup>
 *
 * This is then written as the output image, with the left column giving the
 * index in the image to place the value.
 * 
 * The (x, y) points don't need to be sorted: we do that. You can have 
 * several Ys, each becomes a band in the output LUT. You don't need to
 * start at zero, any integer will do, including negatives.
 *
 * See also: im_identity(), im_invertlut().
 *
 * Returns: 0 on success, -1 on error
 */
int
im_buildlut( DOUBLEMASK *input, IMAGE *output )
{
	State state;

	if( !input || input->xsize < 2 || input->ysize < 1 ) {
		im_error( "im_buildlut", "%s", _( "bad input matrix size" ) );
		return( -1 );
	}

	if( build_state( &state, input ) ||
		buildlut( &state ) ) {
		free_state( &state );
                return( -1 );
	}

        im_initdesc( output,
                state.lut_size, 1, input->xsize - 1, 
		IM_BBITS_DOUBLE, IM_BANDFMT_DOUBLE,
                IM_CODING_NONE, IM_TYPE_HISTOGRAM, 1.0, 1.0, 0, 0 );
        if( im_setupout( output ) ||
		im_writeline( 0, output, (PEL *) state.buf ) ) {
		free_state( &state );
		return( -1 );
	}

	free_state( &state );

	return( 0 );
}
Esempio n. 2
0
void fconfig_setgamma(FakerConfig &fc, double gamma)
{
    fc.gamma = gamma;
    buildlut(fc);
}