diff --git a/commands.c b/commands.c
index ff95f36..20557e5 100644
--- a/commands.c
+++ b/commands.c
@@ -474,6 +474,22 @@ bool i_toggle_antialias(arg_t a)
}
}
+/* a < 0: decrease gamma
+ * a == 0: reset gamma
+ * a > 0: increase gamma
+ */
+bool i_change_gamma(arg_t a)
+{
+ if (mode == MODE_IMAGE) {
+ long val = (long) a;
+ int delta = val > 0 ? 1 : (val < 0 ? -1 : -img.gamma);
+ img_set_gamma(&img, img.gamma + delta);
+ return true;
+ } else {
+ return false;
+ }
+}
+
bool it_toggle_alpha(arg_t a)
{
img.alpha = tns.alpha = !img.alpha;
diff --git a/commands.h b/commands.h
index 118c89a..16aee07 100644
--- a/commands.h
+++ b/commands.h
@@ -67,6 +67,7 @@ bool i_fit_to_img(arg_t);
bool i_rotate(arg_t);
bool i_flip(arg_t);
bool i_toggle_antialias(arg_t);
+bool i_change_gamma(arg_t);
bool it_toggle_alpha(arg_t);
bool it_open_with(arg_t);
bool it_shell_cmd(arg_t);
diff --git a/config.def.h b/config.def.h
index f5d048a..b877aa1 100644
--- a/config.def.h
+++ b/config.def.h
@@ -46,6 +46,12 @@ enum {
GIF_LOOP = 0 /* endless loop [0/1] */
};
+/* gamma correction: the user-visible ranges [-GAMMA_RANGE, 0] and
+ * (0, GAMMA_RANGE] are mapped to the ranges [0, 1], and (1, GAMMA_MAX].
+ * */
+static const double GAMMA_MAX = 10.0;
+static const int GAMMA_RANGE = 32;
+
#endif
#ifdef _THUMBS_CONFIG
@@ -141,6 +147,11 @@ static const keymap_t keys[] = {
{ false, XK_a, i_toggle_antialias, (arg_t) None },
{ false, XK_A, it_toggle_alpha, (arg_t) None },
+ /* decrease/increase/reset gamma */
+ { false, XK_braceleft, i_change_gamma, (arg_t) -1 },
+ { false, XK_braceright, i_change_gamma, (arg_t) +1 },
+ { true, XK_G, i_change_gamma, (arg_t) 0 },
+
/* open current image with given program: */
{ true, XK_g, it_open_with, (arg_t) "gimp" },
diff --git a/image.c b/image.c
index ec248e1..b1c7851 100644
--- a/image.c
+++ b/image.c
@@ -67,6 +67,9 @@ void img_init(img_t *img, win_t *win)
img->alpha = !RENDER_WHITE_ALPHA;
img->multi.cap = img->multi.cnt = 0;
img->multi.animate = false;
+
+ img->cmod = imlib_create_color_modifier();
+ img_set_gamma(img, options->gamma);
}
void exif_auto_orientate(const fileinfo_t *file)
@@ -303,6 +306,8 @@ bool img_load(img_t *img, const fileinfo_t *file)
img_load_gif(img, file);
#endif
+ img_set_gamma(img, img->gamma);
+
img->w = imlib_image_get_width();
img->h = imlib_image_get_height();
img->scalemode = options->scalemode;
@@ -335,6 +340,9 @@ void img_close(img_t *img, bool decache)
imlib_free_image();
img->im = NULL;
}
+
+ if (img->cmod)
+ imlib_context_set_color_modifier(NULL);
}
void img_check_pan(img_t *img, bool moved)
@@ -706,6 +714,28 @@ void img_toggle_antialias(img_t *img)
img->dirty = true;
}
+void img_set_gamma(img_t *img, int gamma)
+{
+ if (img == NULL)
+ return;
+
+ img->gamma = MIN(MAX(gamma, -GAMMA_RANGE), GAMMA_RANGE);
+
+ if (img->im && img->cmod) {
+ if (img->gamma == 0) {
+ imlib_context_set_color_modifier(NULL);
+ } else {
+ double range = img->gamma <= 0 ? 1.0 : GAMMA_MAX - 1.0;
+ imlib_context_set_color_modifier(img->cmod);
+ imlib_reset_color_modifier();
+ imlib_modify_color_modifier_gamma(
+ 1.0 + (double) img->gamma
+ * (range / (double) GAMMA_RANGE));
+ }
+ img->dirty = true;
+ }
+}
+
bool img_frame_goto(img_t *img, int n)
{
if (img == NULL || img->im == NULL)
diff --git a/image.h b/image.h
index 9a4efe6..7ed104e 100644
--- a/image.h
+++ b/image.h
@@ -55,6 +55,9 @@ typedef struct {
bool aa;
bool alpha;
+ Imlib_Color_Modifier cmod;
+ int gamma;
+
multi_img_t multi;
} img_t;
@@ -81,6 +84,8 @@ void img_flip(img_t*, flipdir_t);
void img_toggle_antialias(img_t*);
+void img_set_gamma(img_t*, int);
+
bool img_frame_navigate(img_t*, int);
bool img_frame_animate(img_t*, bool);
diff --git a/main.c b/main.c
index eac3574..376898d 100644
--- a/main.c
+++ b/main.c
@@ -352,6 +352,8 @@ void update_info(void)
n += snprintf(rt + n, rlen - n, "%0*d/%d | ",
fn, img.multi.sel + 1, img.multi.cnt);
}
+ if (img.gamma != 0)
+ n += snprintf(rt + n, rlen - n, "g%d | ", img.gamma);
n += snprintf(rt + n, rlen - n, "%0*d/%d", fw, sel + 1, filecnt);
ow_info = info.script == NULL;
}
diff --git a/options.c b/options.c
index e47ad37..574f871 100644
--- a/options.c
+++ b/options.c
@@ -33,7 +33,7 @@ const options_t *options = (const options_t*) &_options;
void print_usage(void)
{
- printf("usage: sxiv [-bcdFfhioqrstvZ] [-g GEOMETRY] [-n NUM] "
+ printf("usage: sxiv [-bcdFfhioqrstvZ] [-g GEOMETRY] [-G GAMMA] [-n NUM] "
"[-N name] [-z ZOOM] FILES...\n");
}
@@ -44,7 +44,7 @@ void print_version(void)
void parse_options(int argc, char **argv)
{
- int opt, t;
+ int opt, t, gamma;
_options.from_stdin = false;
_options.to_stdout = false;
@@ -53,6 +53,7 @@ void parse_options(int argc, char **argv)
_options.scalemode = SCALE_MODE;
_options.zoom = 1.0;
+ _options.gamma = 0;
_options.fixed_win = false;
_options.fullscreen = false;
@@ -64,7 +65,7 @@ void parse_options(int argc, char **argv)
_options.thumb_mode = false;
_options.clean_cache = false;
- while ((opt = getopt(argc, argv, "bcdFfg:hin:N:oqrstvZz:")) != -1) {
+ while ((opt = getopt(argc, argv, "bcdFfg:G:hin:N:oqrstvZz:")) != -1) {
switch (opt) {
case '?':
print_usage();
@@ -87,6 +88,14 @@ void parse_options(int argc, char **argv)
case 'g':
_options.geometry = optarg;
break;
+ case 'G':
+ if (sscanf(optarg, "%d", &gamma) <= 0) {
+ fprintf(stderr, "sxiv: invalid argument for option -G: %s\n",
+ optarg);
+ exit(EXIT_FAILURE);
+ }
+ _options.gamma = gamma;
+ break;
case 'h':
print_usage();
exit(EXIT_SUCCESS);
diff --git a/options.h b/options.h
index 848a6b2..982602f 100644
--- a/options.h
+++ b/options.h
@@ -34,6 +34,7 @@ typedef struct {
/* image: */
scalemode_t scalemode;
float zoom;
+ int gamma;
/* window: */
bool fixed_win;
diff --git a/sxiv.1 b/sxiv.1
index ee42a00..4c29dbf 100644
--- a/sxiv.1
+++ b/sxiv.1
@@ -49,6 +49,9 @@ Set window position and size. See section GEOMETRY SPECIFICATIONS of X(7) for
more information on
.IR GEOMETRY .
.TP
+.BI "\-G " GAMMA
+Set gamma to GAMMA (-32..32).
+.TP
.BI "\-n " NUM
Start at picture number NUM.
.TP
@@ -282,6 +285,16 @@ Flip image horizontally.
.TP
.B _
Flip image vertically.
+.SS Gamma Correction
+.TP
+.B {
+Decrease gamma.
+.TP
+.B }
+Increase gamma.
+.TP
+.B Ctrl-G
+Reset gamma.
.SS Miscellaneous
.TP
.B a