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Code Issues Releases Activity

plug-ins: Fix signed JPEG 2000 import

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Our JPEG 2000 plug-in assumed all imported images
are unsigned - however, it's possible to store signed data
as well.
This patch adds a check to see if the image has the `sgnd`
flag set to TRUE. If so, we offset the signed data to get it
into the unsigned range before converting to an image.
This commit is contained in:
Alx Sa
2025-08-14 05:27:26 +00:00
parent 6211ec8d2c
commit c35abbe090
1 changed files with 19 additions and 2 deletions
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21
plug-ins/common/file-jp2.c
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@@ -1367,6 +1367,7 @@ load_image (GimpProcedure *procedure,
const Babl *file_format;
gint bpp;
GimpPrecision image_precision;
guint signed_offset;
gint precision_actual, precision_scaled;
gint temp;
gboolean linear = FALSE;
@@ -1594,6 +1595,22 @@ load_image (GimpProcedure *procedure,
precision_scaled = get_valid_precision (precision_actual);
image_precision = get_image_precision (precision_scaled, linear);
signed_offset = 0;
if (image->comps[0].sgnd)
{
switch (precision_scaled)
{
case 32:
signed_offset = G_MAXINT32 - 1;
break;
case 16:
signed_offset = G_MAXINT16 - 1;
break;
default:
signed_offset = G_MAXINT8 - 1;
}
}
gimp_image = gimp_image_new_with_precision (width, height,
base_type, image_precision);
@@ -1623,9 +1640,9 @@ load_image (GimpProcedure *procedure,
for (k = 0; k < width; k++)
{
if (shift >= 0)
temp = image->comps[j].data[i * width + k] << shift;
temp = (image->comps[j].data[i * width + k] + signed_offset) << shift;
else /* precision_actual > 32 */
temp = image->comps[j].data[i * width + k] >> (- shift);
temp = (image->comps[j].data[i * width + k] + signed_offset) >> (- shift);
c = (unsigned char *) &temp;
for (it = 0; it < (precision_scaled / 8); it++)