pdfdraw: Add command line option to gamma correct and invert images.

4 files changed, 59 insertions, 1 deletions

diff --git a/apps/man/pdfdraw.1 b/apps/man/pdfdraw.1
index 67899640..53fbcde9 100644
--- a/apps/man/pdfdraw.1
+++ b/apps/man/pdfdraw.1
@@ -59,6 +59,13 @@ Print the display list used to render each page.
 .TP
 .B \-A
 Disable the use of accelerated functions.
+.TP
+.B \-G gamma
+Gamma correct the output image.
+Some typical values are 0.7 or 1.4 to thin or darken text rendering.
+.TP
+.B \-I
+Invert the output image colors.
 .SH SEE ALSO
 .BR mupdf (1),
 .BR pdfclean (1).
diff --git a/apps/pdfdraw.c b/apps/pdfdraw.c
index 4dd24ff2..a5f6aa1e 100644
--- a/apps/pdfdraw.c
+++ b/apps/pdfdraw.c
@@ -22,6 +22,8 @@ int showmd5 = 0;
 int savealpha = 0;
 int uselist = 1;
 int alphabits = 8;
+float gamma_value = 1;
+int invert = 0;
 
 fz_colorspace *colorspace;
 fz_glyph_cache *glyphcache;
@@ -57,6 +59,8 @@ static void usage(void)
 		"\t-d\tdisable use of display list\n"
 		"\t-5\tshow md5 checksums\n"
 		"\t-R -\trotate clockwise by given number of degrees\n"
+		"\t-G gamma\tgamma correct output\n"
+		"\t-I\tinvert output\n"
 		"\tpages\tcomma separated list of ranges\n");
 	exit(1);
 }
@@ -178,6 +182,11 @@ static void drawpage(pdf_xref *xref, int pagenum)
 			pdf_run_page(xref, page, dev, ctm);
 		fz_free_device(dev);
 
+		if (invert)
+			fz_invert_pixmap(pix);
+		if (gamma_value != 1)
+			fz_gamma_pixmap(pix, gamma_value);
+
 		if (output)
 		{
 			char buf[512];
@@ -295,7 +304,7 @@ int main(int argc, char **argv)
 	fz_error error;
 	int c;
 
-	while ((c = fz_getopt(argc, argv, "o:p:r:R:Aab:dgmtx5")) != -1)
+	while ((c = fz_getopt(argc, argv, "o:p:r:R:Aab:dgmtx5G:I")) != -1)
 	{
 		switch (c)
 		{
@@ -312,6 +321,8 @@ int main(int argc, char **argv)
 		case '5': showmd5++; break;
 		case 'g': grayscale++; break;
 		case 'd': uselist = 0; break;
+		case 'G': gamma_value = atof(fz_optarg); break;
+		case 'I': invert++; break;
 		default: usage(); break;
 		}
 	}
diff --git a/fitz/fitz.h b/fitz/fitz.h
index 7187094f..dff6b8d4 100644
--- a/fitz/fitz.h
+++ b/fitz/fitz.h
@@ -625,6 +625,8 @@ void fz_copy_pixmap_rect(fz_pixmap *dest, fz_pixmap *src, fz_bbox r);
 void fz_premultiply_pixmap(fz_pixmap *pix);
 fz_pixmap *fz_alpha_from_gray(fz_pixmap *gray, int luminosity);
 fz_bbox fz_bound_pixmap(fz_pixmap *pix);
+void fz_invert_pixmap(fz_pixmap *pix);
+void fz_gamma_pixmap(fz_pixmap *pix, float gamma);
 
 fz_pixmap *fz_scale_pixmap(fz_pixmap *src, float x, float y, float w, float h);
 fz_pixmap *fz_scale_pixmap_gridfit(fz_pixmap *src, float x, float y, float w, float h, int gridfit);
diff --git a/fitz/res_pixmap.c b/fitz/res_pixmap.c
index fdd5c357..83f46526 100644
--- a/fitz/res_pixmap.c
+++ b/fitz/res_pixmap.c
@@ -251,6 +251,44 @@ fz_alpha_from_gray(fz_pixmap *gray, int luminosity)
 	return alpha;
 }
 
+void
+fz_invert_pixmap(fz_pixmap *pix)
+{
+	unsigned char *s = pix->samples;
+	int k, x, y;
+
+	for (y = 0; y < pix->h; y++)
+	{
+		for (x = 0; x < pix->w; x++)
+		{
+			for (k = 0; k < pix->n - 1; k++)
+				s[k] = 255 - s[k];
+			s += pix->n;
+		}
+	}
+}
+
+void
+fz_gamma_pixmap(fz_pixmap *pix, float gamma)
+{
+	unsigned char gamma_map[256];
+	unsigned char *s = pix->samples;
+	int k, x, y;
+
+	for (k = 0; k < 256; k++)
+		gamma_map[k] = pow(k / 255.0f, gamma) * 255;
+
+	for (y = 0; y < pix->h; y++)
+	{
+		for (x = 0; x < pix->w; x++)
+		{
+			for (k = 0; k < pix->n - 1; k++)
+				s[k] = gamma_map[s[k]];
+			s += pix->n;
+		}
+	}
+}
+
 /*
  * Write pixmap to PNM file (without alpha channel)
  */