1 files changed, 97 insertions, 0 deletions
diff --git a/lut.c b/lut.c
new file mode 100644
index 0000000..2901355
--- /dev/null
+++ b/lut.c
@@ -0,0 +1,97 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+#include "readers.h"
+#include "viewer.h"
+#include "lut.h"
+
+/* ----------------------------------------------------------------------- */
+
+struct op_map_parm_ch op_map_nothing = {
+    gamma:  1,
+    bottom: 0,
+    top:    255,
+    left:   0,
+    right:  255
+};
+
+struct op_map_lut {
+    unsigned char red[256];
+    unsigned char green[256];
+    unsigned char blue[256];
+};
+
+/* ----------------------------------------------------------------------- */
+/* functions                                                               */
+
+static void build_lut(struct op_map_parm_ch *arg, unsigned char *lut)
+{
+    int i,val;
+    int inrange,outrange;
+    float p;
+
+    inrange  = arg->right - arg->left +1;
+    outrange = arg->top - arg->bottom +1;
+    p = 1/arg->gamma;
+
+    for (i = 0; i < arg->left; i++)
+	lut[i] = 0;
+    for (; i <= arg->right; i++) {
+	val  = pow((float)(i-arg->left)/inrange,p) * outrange + 0.5;
+	val += arg->bottom;
+	if (val < 0)   val = 0;
+	if (val > 255) val = 255;
+	lut[i] = val;
+    }
+    for (; i < 256; i++)
+	lut[i] = 255;
+}
+
+static void*
+op_map_init(struct ida_image *src, struct ida_rect *rect,
+	    struct ida_image_info *i, void *parm)
+{
+    struct op_map_parm *args = parm;
+    struct op_map_lut *lut;
+
+    lut = malloc(sizeof(*lut));
+    build_lut(&args->red,lut->red);
+    build_lut(&args->green,lut->green);
+    build_lut(&args->blue,lut->blue);
+
+    *i = src->i;
+    return lut;
+}
+
+static void
+op_map_work(struct ida_image *src, struct ida_rect *rect,
+	    unsigned char *dst, int line, void *data)
+{
+    struct op_map_lut *lut = data;
+    unsigned char *scanline;
+    int i;
+
+    scanline = src->data + line * src->i.width * 3;
+    memcpy(dst,scanline,src->i.width * 3);
+    if (line < rect->y1 || line >= rect->y2)
+	return;
+    dst      += 3*rect->x1;
+    scanline += 3*rect->x1;
+    for (i = rect->x1; i < rect->x2; i++) {
+	dst[0] = lut->red[scanline[0]];
+	dst[1] = lut->green[scanline[1]];
+	dst[2] = lut->blue[scanline[2]];
+	scanline += 3;
+	dst += 3;
+    }
+}
+
+/* ----------------------------------------------------------------------- */
+
+struct ida_op desc_map = {
+    name:  "map",
+    init:  op_map_init,
+    work:  op_map_work,
+    done:  op_free_done,
+};