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jxl.c: improve jpeg-xl metadata handling #19056

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88ec0c9
jxl.c: Brotli-compress metadata
dholth Jul 8, 2025
f40a8fb
write exif data to separate exv file
dholth Jul 10, 2025
f1f49a3
write exif metadata before writing image
dholth Jul 12, 2025
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21 changes: 21 additions & 0 deletions src/common/exif.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -2442,6 +2442,27 @@ gboolean dt_exif_read(dt_image_t *img,
}
}

int dt_exif_write_exv(uint8_t *blob,
uint32_t size,
const char *path,
const int compressed)
{
try
{
std::unique_ptr<Exiv2::Image> image(Exiv2::ImageFactory::create(Exiv2::ImageType::exv, WIDEN(path)));
image->writeMetadata();
}
catch(const Exiv2::AnyError &e)
{
dt_print(DT_DEBUG_IMAGEIO,
"[exiv2 dt_exif_write_blob] %s: %s",
path,
e.what());
return 0;
}
return 1;
}

int dt_exif_write_blob(uint8_t *blob,
uint32_t size,
const char *path,
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6 changes: 6 additions & 0 deletions src/common/exif.h
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Expand Up @@ -92,6 +92,12 @@ int dt_exif_read_blob(uint8_t **blob, const char *path, const dt_imgid_t imgid,
/** Reads exif tags that are not cached in the database */
void dt_exif_img_check_additional_tags(dt_image_t *img, const char *filename);

/** create empty metadata file */
int dt_exif_write_exv(uint8_t *blob,
uint32_t size,
const char *path,
const int compressed);

/** write blob to file exif. merges with existing exif information.*/
int dt_exif_write_blob(uint8_t *blob, uint32_t size, const char *path, const int compressed);

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14 changes: 7 additions & 7 deletions src/imageio/format/jxl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -309,8 +309,8 @@ int write_image(struct dt_imageio_module_data_t *data,
if(exif && exif_len > 0)
LIBJXL_ASSERT(JxlEncoderUseBoxes(encoder));

/* TODO: workaround; remove when exiv2 implements JXL BMFF write support and use dt_exif_write_blob() after
* closing file instead */
// /* TODO: workaround; remove when exiv2 implements JXL BMFF write support and use dt_exif_write_blob() after
// * closing file instead */
if(exif && exif_len > 0)
{
// Prepend the 4 byte (zero) offset to the blob before writing
Expand All @@ -319,8 +319,8 @@ int write_image(struct dt_imageio_module_data_t *data,
if(!exif_buf)
JXL_FAIL("could not allocate Exif buffer of size %zu", (size_t)(exif_len + 4));
memmove(exif_buf + 4, exif, exif_len);
// Exiv2 < 0.28 doesn't support Brotli compressed boxes
LIBJXL_ASSERT(JxlEncoderAddBox(encoder, "Exif", exif_buf, exif_len + 4, JXL_FALSE));
// Exiv2 >= 0.28 (released 2023-05-08) supports Brotli compressed boxes
LIBJXL_ASSERT(JxlEncoderAddBox(encoder, "Exif", exif_buf, exif_len + 4, JXL_TRUE));
}

/* TODO: workaround; remove when exiv2 implements JXL BMFF write support and update flags() */
Expand All @@ -332,13 +332,13 @@ int write_image(struct dt_imageio_module_data_t *data,
if(xmp_string
&& (xmp_len = strlen(xmp_string)) > 0)
{
// Exiv2 < 0.28 doesn't support Brotli compressed boxes
// Exiv2 >= 0.28 (released 2023-05-08) supports Brotli compressed boxes
LIBJXL_ASSERT(JxlEncoderAddBox(encoder, "xml ",
(const uint8_t *)xmp_string, xmp_len, JXL_FALSE));
(const uint8_t *)xmp_string, xmp_len, JXL_TRUE));
}
}

JxlPixelFormat pixel_format = { 3, JXL_TYPE_FLOAT, JXL_NATIVE_ENDIAN, 0 };
f JxlPixelFormat pixel_format = { 3, JXL_TYPE_FLOAT, JXL_NATIVE_ENDIAN, 0 };

// Fix pixel stride
const size_t pixels_size = width * height * 3 * sizeof(float);
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51 changes: 38 additions & 13 deletions src/imageio/imageio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1436,7 +1436,7 @@ gboolean dt_imageio_export_with_flags(const dt_imgid_t imgid,
if(!ignore_exif
&& (!strcmp(format->mime(NULL), "image/avif")
|| !strcmp(format->mime(NULL), "image/x-exr")
|| !strcmp(format->mime(NULL), "image/jxl")
// || !strcmp(format->mime(NULL), "image/jxl")
|| !strcmp(format->mime(NULL), "image/x-xcf")))
{
const int32_t meta_all =
Expand All @@ -1446,6 +1446,40 @@ gboolean dt_imageio_export_with_flags(const dt_imgid_t imgid,
md_flags_set = metadata ? (metadata->flags & meta_all) == meta_all : FALSE;
}

uint8_t *exif_profile0 = NULL; // Exif data should be 65536 bytes
// max, but if original size is
// close to that, adding new tags
// could make it go over that... so
// let it be and see what happens
// when we write the image
char pathname[PATH_MAX] = { 0 };
gboolean from_cache = TRUE;
dt_image_full_path(imgid, pathname, sizeof(pathname), &from_cache);

// last param is dng mode, it's false here
const int length0 = dt_exif_read_blob(&exif_profile0, pathname, imgid, sRGB,
processed_width, processed_height, FALSE);

char* exv_filename = g_malloc(strlen(filename) + 5);
snprintf(exv_filename, strlen(filename) + 5, "%s%s", filename, ".exv");

// empty metadata file (XXX call write_blob inside there for us)
dt_exif_write_exv(exif_profile0, length0, exv_filename, 1);

// write data into metadata file
dt_exif_write_blob(exif_profile0, length0, exv_filename, 1);

free(exif_profile0);

/* now write xmp into that container, if possible */
if(copy_metadata
&& (format->flags(format_params) & FORMAT_FLAGS_SUPPORT_XMP))
{
dt_exif_xmp_attach_export(imgid, exv_filename, metadata, &dev, &pipe);
// no need to cancel the export if this fail
}

// write image including filtered metadata from .exv
if(!ignore_exif && md_flags_set)
{
uint8_t *exif_profile = NULL; // Exif data should be 65536 bytes
Expand All @@ -1454,12 +1488,8 @@ gboolean dt_imageio_export_with_flags(const dt_imgid_t imgid,
// could make it go over that... so
// let it be and see what happens
// when we write the image
char pathname[PATH_MAX] = { 0 };
gboolean from_cache = TRUE;
dt_image_full_path(imgid, pathname, sizeof(pathname), &from_cache);

// last param is dng mode, it's false here
const int length = dt_exif_read_blob(&exif_profile, pathname, imgid, sRGB,
const int length = dt_exif_read_blob(&exif_profile, exv_filename, imgid, sRGB,
processed_width, processed_height, FALSE);

res = (format->write_image(format_params, filename, outbuf, icc_type,
Expand All @@ -1475,16 +1505,11 @@ gboolean dt_imageio_export_with_flags(const dt_imgid_t imgid,
&pipe, export_masks)) != 0;
}

g_free(exv_filename);

if(res)
goto error;

/* now write xmp into that container, if possible */
if(copy_metadata
&& (format->flags(format_params) & FORMAT_FLAGS_SUPPORT_XMP))
{
dt_exif_xmp_attach_export(imgid, filename, metadata, &dev, &pipe);
// no need to cancel the export if this fail
}

dt_dev_pixelpipe_cleanup(&pipe);
dt_dev_cleanup(&dev);
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