commit b87d6efb6fdca579c23020a93212f8f35375e1fe
Author: Mattias Andrée <[email protected]>
AuthorDate: Sun Jun 4 16:46:14 2017 +0200
Commit: Mattias Andrée <[email protected]>
CommitDate: Sun Jun 4 16:46:14 2017 +0200
Add blind-find-rectangle
Signed-off-by: Mattias Andrée <[email protected]>
diff --git a/Makefile b/Makefile
index be882d8..21e4e1f 100644
--- a/Makefile
+++ b/Makefile
@@ -16,6 +16,7 @@ BIN =\
blind-disperse\
blind-dissolve\
blind-extend\
+ blind-find-rectangle\
blind-flip\
blind-flop\
blind-from-image\
diff --git a/README b/README
index eb2d574..8b0b49a 100644
--- a/README
+++ b/README
@@ -48,6 +48,9 @@ UTILITIES
blind-extend(1)
Add margins to a video
+ blind-find-rectangle(1)
+ Locate a coloured rectangle
+
blind-flip(1)
Mirror a video vertically
diff --git a/man/blind-find-rectangle.1 b/man/blind-find-rectangle.1
new file mode 100644
index 0000000..beb16fa
--- /dev/null
+++ b/man/blind-find-rectangle.1
@@ -0,0 +1,70 @@
+.TH BLIND-FIND-RECTANGLE 1 blind
+.SH NAME
+blind-find-rectangle - Locate a coloured rectangle
+.SH SYNOPSIS
+.B blind-find-rectangle
+[-a
+.IR min-area ]
+[-h
+.IR min-height ]
+[-w
+.IR min-width ]
+.I X
+.I Y
+.I Z
+.RI [ alpha ]
+.SH DESCRIPTION
+.B blind-find-rectangle
+reads a video from stdin, and locates the largest
+rectangle of a specified colour. If there are two
+or more maximal rectangles, one is choosen arbitrarily.
+The specified by the arguments
+.IR X ,
+.IR Y ,
+and
+.IR Z ,
+and the selected
+.I alpha
+value. The colour is specified in CIE XYZ. If
+.I X
+and
+.I Z
+are not specified, the colour will be CIE Standard Illuminant
+D65-grey with the luminosity
+.IR Y .
+If
+.I alpha
+is not specified, 1, which means fully opaque, will be used.
+.SH STDOUT
+The location and dimensions of the rectangle is printed stdout.
+Exactly one line is printed per frame. Each line has the format
+.nf
+
+ \fB"%zu %zu %zu %zu\\n"\fP, <\fIleft\fP>, <\fItop\fP>, <\fIwidth\fP>,
<\fIheight\fP>
+
+.fi
+where
+.I left
+is position on the X-axis (measured from the left) on the
+left-most pixels in the rectangle,
+.I top
+is position on the Y-axis (measured from the top) on the
+top-most pixels in the rectangle,
+.I width
+is the width of the rectangle, and
+.I height
+is the width of the rectangle.
+.SH NOTES
+.B blind-find-rectangle
+may be changed in the future to use some other colour model,
+therefore, it is recommended to also use
+.BR blind-colour-ciexyz (1)
+if you are specifying the colour in CIE XYZ. If however
+your values are colour space-agnostic, you should not.
+.SH SEE ALSO
+.BR blind (7),
+.BR blind-colour-ciexyz (1),
+.BR blind-colour-srgb (1)
+.SH AUTHORS
+Mattias Andrée
+.RI < [email protected] >
diff --git a/man/blind.7 b/man/blind.7
index b811440..ff3f479 100644
--- a/man/blind.7
+++ b/man/blind.7
@@ -61,6 +61,9 @@ Framewise split a video into multiple videos
.BR blind-extend (1)
Add margins to a video
.TP
+.BR blind-find-rectangle (1)
+Locate a coloured rectangle
+.TP
.BR blind-flip (1)
Mirror a video vertically
.TP
diff --git a/src/blind-find-rectangle.c b/src/blind-find-rectangle.c
new file mode 100644
index 0000000..87d2734
--- /dev/null
+++ b/src/blind-find-rectangle.c
@@ -0,0 +1,135 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+USAGE("[-a min-area] [-h min-height] [-w min-width] X Y Z [alpha]")
+
+struct pair {
+ size_t x;
+ size_t w;
+};
+
+static struct stream stream;
+static double X, Y, Z, alpha = 1;
+static size_t min_width = 1;
+static size_t min_height = 1;
+static size_t min_area = 1;
+static struct pair *stack = NULL;
+static size_t *cache = NULL;
+static char *buf = NULL;
+
+static void
+process(const void *colour)
+{
+ size_t y, x, x0, w, w0, h, top, area;
+ size_t best_area, x1, x2, y1, y2;
+ for (;;) {
+ top = x1 = x2 = y1 = y2 = best_area = 0;
+ memset(cache, 0, (stream.width + 1) * sizeof(*cache));
+ for (y = 0; eread_row(&stream, buf); y++) {
+ w = 0;
+ for (x = 0; x <= stream.width; x++) {
+ if (x != stream.width) {
+ if (!memcmp(buf + x *
stream.pixel_size, colour, stream.pixel_size))
+ cache[x] += 1;
+ else
+ cache[x] = 0;
+ }
+ if (cache[x] > w) {
+ stack[top].x = x;
+ stack[top++].w = w;
+ w = cache[x];
+ } else if (cache[x] < w) {
+ do {
+ x0 = stack[--top].x;
+ w0 = stack[top].w;
+ area = w * (x - x0);
+ if (area > best_area) {
+ best_area = area;
+ x1 = x0;
+ x2 = x - 1;
+ y1 = y - w + 1;
+ y2 = y;
+ }
+ w = w0;
+ } while (cache[x] < w);
+ if ((w = cache[x])) {
+ stack[top].x = x0;
+ stack[top++].w = w0;
+ }
+ }
+ }
+ fprintf(stderr, "%zu\n", y);
+ }
+ if (!y)
+ break;
+ w = x2 - x1 + 1;
+ h = y2 - y1 + 1;
+ if (best_area < min_area || w < min_width || h < min_height)
+ printf("0 0 0 0\n");
+ else
+ printf("%zu %zu %zu %zu\n", x1, y1, w, h);
+ }
+}
+
+int
+main(int argc, char *argv[])
+{
+ double colour_lf[4];
+ double colour_f[4];
+
+ ARGBEGIN {
+ case 'a':
+ min_area = etozu_flag('a', UARGF(), 1, SIZE_MAX);
+ break;
+ case 'h':
+ min_height = etozu_flag('h', UARGF(), 1, SIZE_MAX);
+ break;
+ case 'w':
+ min_width = etozu_flag('w', UARGF(), 1, SIZE_MAX);
+ break;
+ default:
+ usage();
+ } ARGEND;
+
+ if (argc != 3 && argc != 4)
+ usage();
+
+ X = etolf_arg("the X value", argv[0]);
+ Y = etolf_arg("the Y value", argv[1]);
+ Z = etolf_arg("the Z value", argv[2]);
+ if (argc > 3)
+ alpha = etolf_arg("the alpha value", argv[3]);
+
+ eopen_stream(&stream, NULL);
+ echeck_dimensions(&stream, WIDTH, NULL);
+ if (stream.width == SIZE_MAX)
+ eprintf("video is too wide\n");
+ if (stream.width > SIZE_MAX / stream.height)
+ eprintf("video is too large\n");
+
+ stack = emalloc2(stream.width + 1, sizeof(*stack));
+ cache = emalloc2(stream.width + 1, sizeof(*cache));
+ buf = emalloc(stream.row_size);
+
+ if (!strcmp(stream.pixfmt, "xyza")) {
+ colour_lf[0] = X;
+ colour_lf[1] = Y;
+ colour_lf[2] = Z;
+ colour_lf[3] = alpha;
+ process(colour_lf);
+ } else if (!strcmp(stream.pixfmt, "xyza f")) {
+ colour_f[0] = (float)X;
+ colour_f[1] = (float)Y;
+ colour_f[2] = (float)Z;
+ colour_f[3] = (float)alpha;
+ process(colour_f);
+ } else {
+ eprintf("pixel format %s is not supported, try xyza\n",
stream.pixfmt);
+ }
+
+ fshut(stdout, "<stdout>");
+ free(stack);
+ free(cache);
+ free(buf);
+ return 0;
+}
