/*
* ... FIXME: docs
*/
static void
print_summary (struct jpeg_decompress_struct *cinfo,
gint num_quant_tables)
{
gint quality;
gint i;
GSList *source_list;
/* detect JPEG quality - test the formula used in the jpeg plug-in */
quality = jpeg_detect_quality (cinfo);
if (quality > 0)
g_print ("\tQuality: %02d (exact)\n", quality);
else if (quality < 0)
g_print ("\tQuality: %02d (approx)\n", -quality);
else
g_print ("\tQuality: unknown\n");
/* JPEG sampling factors */
g_print ("\tSampling: %dx%d",
cinfo->comp_info[0].h_samp_factor,
cinfo->comp_info[0].v_samp_factor);
if ((cinfo->num_components > 1 && cinfo->num_components != 3)
|| cinfo->comp_info[1].h_samp_factor != 1
|| cinfo->comp_info[1].v_samp_factor != 1
|| cinfo->comp_info[2].h_samp_factor != 1
|| cinfo->comp_info[2].v_samp_factor != 1)
{
for (i = 1; i < cinfo->num_components; i++)
g_print (",%dx%d",
cinfo->comp_info[i].h_samp_factor,
cinfo->comp_info[i].v_samp_factor);
}
g_print ("\n");
/* Number of quantization tables */
g_print ("\tQ.tables: %d\n", num_quant_tables);
source_list = detect_source (cinfo, num_quant_tables);
if (source_list)
{
GSList *l;
guint32 hash;
guint32 hash_t;
hash = hash_quant_tables (cinfo);
hash_t = hash_transposed_quant_tables (cinfo);
for (l = source_list; l; l = l->next)
{
QuantInfo *source_info = l->data;
const gchar *comment = "";
if (source_info->hash == hash)
comment = "";
else if (source_info->hash == hash_t)
comment = " (rotated)";
else if (num_quant_tables == 1)
comment = " (grayscale)";
else
comment = " (FALSE MATCH)";
g_print ("\tSource: %s - %s%s\n",
source_info->source_name,
source_info->setting_name,
comment);
}
g_slist_free (source_list);
}
else
g_print ("\tSource: unknown\n");
}
/**
* jpeg_detect_original_settings:
* @cinfo: a pointer to a JPEG decompressor info.
* @image_ID: the image to which the parasite should be attached.
*
* Analyze the image being decompressed (@cinfo) and extract the
* sampling factors, quantization tables and overall image quality.
* Store this information in a parasite and attach it to @image_ID.
*
* This function must be called after jpeg_read_header() so that
* @cinfo contains the quantization tables and the sampling factors
* for each component.
*
* Return Value: TRUE if a parasite has been attached to @image_ID.
*/
gboolean
jpeg_detect_original_settings (struct jpeg_decompress_struct *cinfo,
gint32 image_ID)
{
guint parasite_size;
guchar *parasite_data;
GimpParasite *parasite;
guchar *dest;
gint quality;
gint num_quant_tables = 0;
gint t;
gint i;
g_return_val_if_fail (cinfo != NULL, FALSE);
if (cinfo->jpeg_color_space == JCS_UNKNOWN
|| cinfo->out_color_space == JCS_UNKNOWN)
return FALSE;
quality = jpeg_detect_quality (cinfo);
/* no need to attach quantization tables if they are the ones from IJG */
if (quality <= 0)
{
for (t = 0; t < 4; t++)
if (cinfo->quant_tbl_ptrs[t])
num_quant_tables++;
}
parasite_size = 4 + cinfo->num_components * 2 + num_quant_tables * 128;
parasite_data = g_new (guchar, parasite_size);
dest = parasite_data;
*dest++ = CLAMP0255 (cinfo->jpeg_color_space);
*dest++ = ABS (quality);
*dest++ = CLAMP0255 (cinfo->num_components);
*dest++ = num_quant_tables;
for (i = 0; i < cinfo->num_components; i++)
{
*dest++ = CLAMP0255 (cinfo->comp_info[i].h_samp_factor);
*dest++ = CLAMP0255 (cinfo->comp_info[i].v_samp_factor);
}
if (quality <= 0)
{
for (t = 0; t < 4; t++)
if (cinfo->quant_tbl_ptrs[t])
for (i = 0; i < DCTSIZE2; i++)
{
guint16 c = cinfo->quant_tbl_ptrs[t]->quantval[i];
*dest++ = c / 256;
*dest++ = c & 255;
}
}
parasite = gimp_parasite_new ("jpeg-settings",
GIMP_PARASITE_PERSISTENT,
parasite_size,
parasite_data);
g_free (parasite_data);
gimp_image_parasite_attach (image_ID, parasite);
gimp_parasite_free (parasite);
return TRUE;
}
static void
add_unknown_table (struct jpeg_decompress_struct *cinfo,
gchar *filename)
{
guint32 hashval;
GSList *list;
QuantTableData *table_data;
gint num_quant_tables;
gint t;
gint i;
hashval = hash_quant_tables (cinfo);
/* linear search - the number of unknown tables is usually very small */
for (list = found_tables; list; list = list->next)
{
table_data = list->data;
if (table_data->hashval == hashval
&& table_data->subsmp_h == cinfo->comp_info[0].h_samp_factor
&& table_data->subsmp_v == cinfo->comp_info[0].v_samp_factor)
{
/* this unknown table has already been seen in previous files */
table_data->files = g_slist_prepend (table_data->files, filename);
return;
}
}
/* not found => new table */
table_data = g_new (QuantTableData, 1);
table_data->hashval = hashval;
table_data->subsmp_h = cinfo->comp_info[0].h_samp_factor;
table_data->subsmp_v = cinfo->comp_info[0].v_samp_factor;
num_quant_tables = 0;
for (t = 0; t < 4; t++)
if (cinfo->quant_tbl_ptrs[t])
num_quant_tables++;
table_data->num_quant_tables = num_quant_tables;
table_data->ijg_qual = jpeg_detect_quality (cinfo);
table_data->files = g_slist_prepend (NULL, filename);
if (cinfo->quant_tbl_ptrs[0])
{
for (i = 0; i < DCTSIZE2; i++)
table_data->luminance[i] = cinfo->quant_tbl_ptrs[0]->quantval[i];
}
else
{
for (i = 0; i < DCTSIZE2; i++)
table_data->luminance[i] = 0;
}
if (cinfo->quant_tbl_ptrs[1])
{
for (i = 0; i < DCTSIZE2; i++)
table_data->chrominance[i] = cinfo->quant_tbl_ptrs[1]->quantval[i];
}
else
{
for (i = 0; i < DCTSIZE2; i++)
table_data->chrominance[i] = 0;
}
found_tables = g_slist_prepend (found_tables, table_data);
}