From 72bf913f3d96a3260824361f9b410e32cc0d17e7 Mon Sep 17 00:00:00 2001 From: Přemysl Eric Janouch Date: Tue, 10 Oct 2023 09:31:13 +0200 Subject: Add a tool to find hot pixels It works well for my Nikon. Note that hot pixels can be eliminated in the camera itself, when you run sensor cleaning immediately after a very long exposure of darkness. --- tools/hotpixels.c | 210 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 210 insertions(+) create mode 100644 tools/hotpixels.c (limited to 'tools') diff --git a/tools/hotpixels.c b/tools/hotpixels.c new file mode 100644 index 0000000..ee1028c --- /dev/null +++ b/tools/hotpixels.c @@ -0,0 +1,210 @@ +// +// hotpixels.c: look for hot pixels in raw image files +// +// Usage: pass a bunch of raw photo images taken with the lens cap on at, +// e.g., ISO 8000-12800 @ 1/20-1/60, and store the resulting file as, +// e.g., Nikon D7500.badpixels, which can then be directly used by Rawtherapee. +// +// Copyright (c) 2023, Přemysl Eric Janouch +// +// Permission to use, copy, modify, and/or distribute this software for any +// purpose with or without fee is hereby granted. +// +// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES +// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY +// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION +// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN +// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +// + +#include + +#if LIBRAW_VERSION < LIBRAW_MAKE_VERSION(0, 21, 0) +#error LibRaw 0.21.0 or newer is required. +#endif + +#include +#include +#include +#include +#include + +static void * +xreallocarray(void *o, size_t n, size_t m) +{ + if (m && n > SIZE_MAX / m) { + fprintf(stderr, "xreallocarray: %s\n", strerror(ENOMEM)); + exit(EXIT_FAILURE); + } + void *p = realloc(o, n * m); + if (!p && n && m) { + fprintf(stderr, "xreallocarray: %s\n", strerror(errno)); + exit(EXIT_FAILURE); + } + return p; +} + +// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + +struct coord { ushort x, y; }; + +static bool +coord_equals(struct coord a, struct coord b) +{ + return a.x == b.x && a.y == b.y; +} + +static int +coord_cmp(const void *a, const void *b) +{ + const struct coord *ca = (const struct coord *) a; + const struct coord *cb = (const struct coord *) b; + return ca->y != cb->y + ? (int) ca->y - (int) cb->y + : (int) ca->x - (int) cb->x; +} + +struct candidates { + struct coord *xy; + size_t len; + size_t alloc; +}; + +static void +candidates_add(struct candidates *c, ushort x, ushort y) +{ + if (c->len == c->alloc) { + c->alloc += 64; + c->xy = xreallocarray(c->xy, sizeof *c->xy, c->alloc); + } + + c->xy[c->len++] = (struct coord) {x, y}; +} + +// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + +// A stretch of zeroes that is assumed to mean start of outliers. +#define SPAN 10 + +static const char * +process_raw(struct candidates *c, const uint8_t *p, size_t len) +{ + libraw_data_t *iprc = libraw_init(LIBRAW_OPIONS_NO_DATAERR_CALLBACK); + if (!iprc) + return "failed to obtain a LibRaw handle"; + + int err = 0; + if ((err = libraw_open_buffer(iprc, p, len)) || + (err = libraw_unpack(iprc))) { + libraw_close(iprc); + return libraw_strerror(err); + } + if (!iprc->rawdata.raw_image) { + libraw_close(iprc); + return "only Bayer raws are supported, not Foveon"; + } + + // Make a histogram. + uint64_t bins[USHRT_MAX] = {}; + for (ushort yy = 0; yy < iprc->sizes.height; yy++) { + for (ushort xx = 0; xx < iprc->sizes.width; xx++) { + ushort y = iprc->sizes.top_margin + yy; + ushort x = iprc->sizes.left_margin + xx; + bins[iprc->rawdata.raw_image[y * iprc->sizes.raw_width + x]]++; + } + } + + // Detecting outliers is not completely straight-forward, + // it may help to see the histogram. + if (getenv("HOTPIXELS_HISTOGRAM")) { + for (ushort i = 0; i < USHRT_MAX; i++) + fprintf(stderr, "%u ", (unsigned) bins[i]); + fputc('\n', stderr); + } + + // Go to the first non-zero pixel value. + size_t last = 0; + for (; last < USHRT_MAX; last++) + if (bins[last]) + break; + + // Find the last pixel value we assume to not be hot. + for (; last < USHRT_MAX - SPAN - 1; last++) { + uint64_t nonzero = 0; + for (int i = 1; i <= SPAN; i++) + nonzero += bins[last + i]; + if (!nonzero) + break; + } + + // Store coordinates for all pixels above that value. + for (ushort yy = 0; yy < iprc->sizes.height; yy++) { + for (ushort xx = 0; xx < iprc->sizes.width; xx++) { + ushort y = iprc->sizes.top_margin + yy; + ushort x = iprc->sizes.left_margin + xx; + if (iprc->rawdata.raw_image[y * iprc->sizes.raw_width + x] > last) + candidates_add(c, xx, yy); + } + } + + libraw_close(iprc); + return NULL; +} + +// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + +static const char * +do_file(struct candidates *c, const char *filename) +{ + FILE *fp = fopen(filename, "rb"); + if (!fp) + return strerror(errno); + + uint8_t *data = NULL, buf[256 << 10]; + size_t n, len = 0; + while ((n = fread(buf, sizeof *buf, sizeof buf / sizeof *buf, fp))) { + data = xreallocarray(data, len + n, 1); + memcpy(data + len, buf, n); + len += n; + } + + const char *err = ferror(fp) + ? strerror(errno) + : process_raw(c, data, len); + + fclose(fp); + free(data); + return err; +} + +int +main(int argc, char *argv[]) +{ + struct candidates c = {}; + for (int i = 1; i < argc; i++) { + const char *filename = argv[i], *err = do_file(&c, filename); + if (err) { + fprintf(stderr, "%s: %s\n", filename, err); + return EXIT_FAILURE; + } + } + + qsort(c.xy, c.len, sizeof *c.xy, coord_cmp); + + // If it is detected in all passed photos, it is probably indeed bad. + int count = 1; + for (size_t i = 1; i <= c.len; i++) { + if (i != c.len && coord_equals(c.xy[i - 1], c.xy[i])) { + count++; + continue; + } + + if (count == argc - 1) + printf("%u %u\n", c.xy[i - 1].x, c.xy[i - 1].y); + + count = 1; + } + return 0; +} -- cgit v1.2.3-70-g09d2