pango_image: Add basic Tiff loading support.

Author: stevenlovegrove

components/pango_image/CMakeLists.txt

@@ -26,7 +26,7 @@ option(BUILD_PANGOLIN_LIBTIFF "Build support for libtiff image input" ON)
 if(BUILD_PANGOLIN_LIBTIFF)
     find_package(TIFF QUIET)
     if(TIFF_FOUND)
-        target_compile_definitions(${COMPONENT} PRIVATE HAVE_TIFF)
+        target_compile_definitions(${COMPONENT} PRIVATE HAVE_LIBTIFF)
         target_include_directories(${COMPONENT} PRIVATE ${TIFF_INCLUDE_DIR} )
         target_link_libraries(${COMPONENT} PRIVATE ${TIFF_LIBRARY})
         message(STATUS "libtiff Found and Enabled")
@@ -99,6 +99,7 @@ PRIVATE
     ${CMAKE_CURRENT_LIST_DIR}/src/image_io_bmp.cpp
     ${CMAKE_CURRENT_LIST_DIR}/src/image_io_zstd.cpp
     ${CMAKE_CURRENT_LIST_DIR}/src/image_io_libraw.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/image_io_tiff.cpp
 )
 
 target_link_libraries(${COMPONENT} PUBLIC pango_core)

components/pango_image/src/image_io.cpp

@@ -73,6 +73,9 @@ void SavePacked12bit(const Image<unsigned char>& image, const pangolin::PixelFor
 // LibRaw raw camera files
 TypedImage LoadLibRaw(const std::string& filename);
 
+// TIFF
+TypedImage LoadTiff(const std::string& filename);
+
 TypedImage LoadImage(std::istream& in, ImageFileType file_type)
 {
     switch (file_type) {
@@ -118,9 +121,9 @@ TypedImage LoadImage(const std::string& filename, ImageFileType file_type)
     case ImageFileTypePango:
         return LoadPango(filename);
     case ImageFileTypeArw:
-        [[fallthrough]];
-    case ImageFileTypeTiff:
         return LoadLibRaw(filename);
+    case ImageFileTypeTiff:
+        return LoadTiff(filename);
     default:
         throw std::runtime_error("Unsupported image file type, '" + filename + "'");
     }

components/pango_image/src/image_io_tiff.cpp

@@ -0,0 +1,78 @@
+#include <cassert>
+#include <pangolin/image/typed_image.h>
+
+#ifdef HAVE_LIBTIFF
+#  include <tiffio.h>
+#endif
+
+namespace pangolin {
+
+#ifdef HAVE_LIBTIFF
+template<typename T>
+T GetOrThrow(TIFF* tif, uint32_t tag)
+{
+    T r;
+    if (TIFFGetField(tif, tag, &r) != 1) {
+        throw std::runtime_error("Expected tag missing when reading tiff (" + std::to_string(tag) + ")");
+    }
+    return r;
+}
+
+template<typename T>
+T GetOrDefault(TIFF* tif, uint32_t tag, T default_val)
+{
+    T r = default_val;
+    TIFFGetField(tif, tag, &r);
+    return r;
+}
+#endif
+
+TypedImage LoadTiff(
+    const std::string& filename
+) {
+#ifdef HAVE_LIBTIFF
+    TIFF* tif = TIFFOpen(filename.c_str(),"r");
+    if (!tif) {
+        throw std::runtime_error("libtiff failed to open " + filename);
+    }
+
+    const auto width = GetOrThrow<uint32_t>(tif, TIFFTAG_IMAGEWIDTH);
+    const auto height = GetOrThrow<uint32_t>(tif, TIFFTAG_IMAGELENGTH);
+    const auto channels = GetOrThrow<uint16_t>(tif, TIFFTAG_SAMPLESPERPIXEL);
+    const auto bits_per_channel = GetOrThrow<uint16_t>(tif, TIFFTAG_BITSPERSAMPLE);
+    const auto sample_format = GetOrDefault<uint16_t>(tif, TIFFTAG_SAMPLEFORMAT, SAMPLEFORMAT_UINT);
+    const auto planar = GetOrThrow<uint16_t>(tif, TIFFTAG_PLANARCONFIG);
+//    const auto photom = GetOrThrow<uint16_t>(tif, TIFFTAG_PHOTOMETRIC);
+
+    assert(width >= 0 && height >= 0 && channels >= 0 && bits_per_channel > 0);
+
+    if(planar != PLANARCONFIG_CONTIG /*|| photom != PHOTOMETRIC_RGB*/ || bits_per_channel % 8 != 0 || !(channels == 1 || channels == 3))
+        throw std::runtime_error("TIFF support is currently limited. Consider contributing to image_io_tiff.cpp.");
+
+    std::string sfmt;
+    switch(sample_format) {
+    case SAMPLEFORMAT_UINT: sfmt = (channels == 3) ? "RGB24" : "GRAY8"; break;
+    case SAMPLEFORMAT_IEEEFP: sfmt = (channels == 3) ? "RGB96F" : "GRAY32F"; break;
+    default: throw std::runtime_error("TIFF support is currently limited. Consider contributing to image_io_tiff.cpp.");
+    }
+
+    TypedImage image(width, height, PixelFormatFromString(sfmt));
+    const tsize_t scanlength_bytes = TIFFScanlineSize(tif);
+    if(scanlength_bytes != image.pitch)
+        throw std::runtime_error("TIFF: unexpected scanline length");
+
+    for (size_t row = 0; row < height; ++row) {
+        TIFFReadScanline(tif, image.RowPtr(row), row);
+    }
+
+    TIFFClose(tif);
+
+    return image;
+#else
+    PANGOLIN_UNUSED(filename);
+    throw std::runtime_error("Rebuild Pangolin for libtiff support.");
+#endif
+}
+
+}
+