static OPJ_CODEC_FORMAT format_from_header(const unsigned char mem[JP2_FILEHEADER_SIZE])
{
if (check_jp2(mem)) {
return OPJ_CODEC_JP2;
}
else if (check_j2k(mem)) {
return OPJ_CODEC_J2K;
}
else {
return OPJ_CODEC_UNKNOWN;
}
}
struct ImBuf *imb_jp2_decode(unsigned char *mem, size_t size, int flags, char colorspace[IM_MAX_SPACE])
{
struct ImBuf *ibuf = NULL;
bool use_float = false; /* for precision higher then 8 use float */
bool use_alpha = false;
long signed_offsets[4] = {0, 0, 0, 0};
int float_divs[4] = {1, 1, 1, 1};
unsigned int i, i_next, w, h, planes;
unsigned int y;
int *r, *g, *b, *a; /* matching 'opj_image_comp.data' type */
int is_jp2, is_j2k;
opj_dparameters_t parameters; /* decompression parameters */
opj_event_mgr_t event_mgr; /* event manager */
opj_image_t *image = NULL;
opj_dinfo_t *dinfo = NULL; /* handle to a decompressor */
opj_cio_t *cio = NULL;
is_jp2 = check_jp2(mem);
is_j2k = check_j2k(mem);
if (!is_jp2 && !is_j2k)
return(NULL);
/* both 8, 12 and 16 bit JP2Ks are default to standard byte colorspace */
colorspace_set_default_role(colorspace, IM_MAX_SPACE, COLOR_ROLE_DEFAULT_BYTE);
/* configure the event callbacks (not required) */
memset(&event_mgr, 0, sizeof(opj_event_mgr_t));
event_mgr.error_handler = error_callback;
event_mgr.warning_handler = warning_callback;
event_mgr.info_handler = info_callback;
/* set decoding parameters to default values */
opj_set_default_decoder_parameters(¶meters);
/* JPEG 2000 compressed image data */
/* get a decoder handle */
dinfo = opj_create_decompress(is_jp2 ? CODEC_JP2 : CODEC_J2K);
/* catch events using our callbacks and give a local context */
opj_set_event_mgr((opj_common_ptr)dinfo, &event_mgr, stderr);
/* setup the decoder decoding parameters using the current image and user parameters */
opj_setup_decoder(dinfo, ¶meters);
/* open a byte stream */
cio = opj_cio_open((opj_common_ptr)dinfo, mem, size);
/* decode the stream and fill the image structure */
image = opj_decode(dinfo, cio);
if (!image) {
fprintf(stderr, "ERROR -> j2k_to_image: failed to decode image!\n");
opj_destroy_decompress(dinfo);
opj_cio_close(cio);
return NULL;
}
/* close the byte stream */
opj_cio_close(cio);
if ((image->numcomps * image->x1 * image->y1) == 0) {
fprintf(stderr, "\nError: invalid raw image parameters\n");
return NULL;
}
w = image->comps[0].w;
h = image->comps[0].h;
switch (image->numcomps) {
case 1: /* Grayscale */
case 3: /* Color */
planes = 24;
use_alpha = false;
break;
default: /* 2 or 4 - Grayscale or Color + alpha */
planes = 32; /* grayscale + alpha */
use_alpha = true;
break;
}
i = image->numcomps;
if (i > 4) i = 4;
while (i) {
i--;
if (image->comps[i].prec > 8)
use_float = true;
if (image->comps[i].sgnd)
signed_offsets[i] = 1 << (image->comps[i].prec - 1);
/* only needed for float images but dosnt hurt to calc this */
float_divs[i] = (1 << image->comps[i].prec) - 1;
}
ibuf = IMB_allocImBuf(w, h, planes, use_float ? IB_rectfloat : IB_rect);
if (ibuf == NULL) {
if (dinfo)
opj_destroy_decompress(dinfo);
return NULL;
}
ibuf->ftype = JP2;
if (is_jp2)
ibuf->ftype |= JP2_JP2;
else
ibuf->ftype |= JP2_J2K;
if (use_float) {
float *rect_float = ibuf->rect_float;
if (image->numcomps < 3) {
r = image->comps[0].data;
a = (use_alpha) ? image->comps[1].data : NULL;
/* grayscale 12bits+ */
if (use_alpha) {
a = image->comps[1].data;
PIXEL_LOOPER_BEGIN(rect_float) {
rect_float[0] = rect_float[1] = rect_float[2] = (float)(r[i] + signed_offsets[0]) / float_divs[0];
rect_float[3] = (a[i] + signed_offsets[1]) / float_divs[1];
}
PIXEL_LOOPER_END;
}
else {
PIXEL_LOOPER_BEGIN(rect_float) {
rect_float[0] = rect_float[1] = rect_float[2] = (float)(r[i] + signed_offsets[0]) / float_divs[0];
rect_float[3] = 1.0f;
}
PIXEL_LOOPER_END;
}
}
