Function makeGrayQuantIndexTable

deps/leptonica/src/grayquant.c:1842–1863

----------------------------------------------------------------------* * Quantization tables for linear thresholds of grayscale images * *----------------------------------------------------------------------*/ ! * \brief makeGrayQuantIndexTable() * * \param[in] nlevels number of output levels * \return table maps input gray level to colormap index, * or NU

 * </pre>
 */
l_int32 *
makeGrayQuantIndexTable(l_int32  nlevels)
{
l_int32   *tab;
l_int32    i, j, thresh;

    PROCNAME("makeGrayQuantIndexTable");

    if ((tab = (l_int32 *)LEPT_CALLOC(256, sizeof(l_int32))) == NULL)
        return (l_int32 *)ERROR_PTR("calloc fail for tab", procName, NULL);
    for (i = 0; i < 256; i++) {
        for (j = 0; j < nlevels; j++) {
            thresh = 255 * (2 * j + 1) / (2 * nlevels - 2);
            if (i <= thresh) {
                tab[i] = j;
/*                fprintf(stderr, "tab[%d] = %d\n", i, j); */
                break;
            }
        }
    }
    return tab;
}


/*!