Add support to retrieve height from a DNL marker segment.

DNL markers are part of the official JPEG-LS standard (but almost never used). Add support to scan the buffer for this
marker segment if the height is zero.
By design CharLS itself will never write DNL marker segment as it always knows the height of the image before it writes the SOF marker segment.

CHANGELOG.md

@@ -9,14 +9,15 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/)
 ### Added
 
 - Support to encode and decode mapping tables.
+- Support to retrieve the height from a DNL marker segment.
 
 ### Changed
 
 - BREAKING: Updated the minimal required C++ language version to C++17.
 - BREAKING: encoding_options::include_pc_parameters_jai is not enabled by default anymore.
 - BREAKING: charls::jpegls_decoder and charls::jpegls_encoder follow the same const pattern as the C API.
 - BREAKING: the failure values of the enum charls::jpegls_errc are now divided in 2 groups: runtime failures and logic.
-- BREAKING: The public charls.h header has been split into charls.h (C users) and charls.hpp (C++ users).
+- BREAKING: The public charls.h header has been split into charls.h (C applications) and charls.hpp (C++ applications).
 
 ### Removed
 

README.md

@@ -35,13 +35,12 @@ According to preliminary test results published on <https://imagecompression.inf
 The following JPEG-LS options are not supported by the CharLS implementation. Most of these options are rarely used in practice.
 
 * No support to encode JPEG restart markers  
-  Decoding is supported, but no recovery mechanisme is implemented for corrupted JPEG-LS files.
+  Decoding is supported, but no recovery mechanism is implemented for corrupted JPEG-LS files.
 * No support for sub-sampled scans.
   Sub-sampling is a lossly encoding mechanism and not used in lossless scenarios.
 * No support for multi component frames with mixed component counts in a single scan.
   While technical possible all known JPEG-LS codecs put multi-component (color) images in a single scan
   or in multiple scans, but not use a mix of these in one file.
-* No support to encode\decode images with the height defined after the first scan (DNL marker).
 * No support for point transform.
   Point transform is a lossly encoding mechanism and not used in lossless scenarios.
 

include/charls/public_types.h

@@ -44,7 +44,7 @@ enum charls_jpegls_errc
     CHARLS_JPEGLS_ERRC_START_OF_IMAGE_MARKER_NOT_FOUND = 11,
     CHARLS_JPEGLS_ERRC_INVALID_SPIFF_HEADER = 12,
     CHARLS_JPEGLS_ERRC_UNKNOWN_JPEG_MARKER_FOUND = 13,
-    CHARLS_JPEGLS_ERRC_UNEXPECTED_MARKER_FOUND = 14,
+    CHARLS_JPEGLS_ERRC_UNEXPECTED_START_OF_SCAN_MARKER = 14,
     CHARLS_JPEGLS_ERRC_INVALID_MARKER_SEGMENT_SIZE = 15,
     CHARLS_JPEGLS_ERRC_DUPLICATE_START_OF_IMAGE_MARKER = 16,
     CHARLS_JPEGLS_ERRC_DUPLICATE_START_OF_FRAME_MARKER = 17,
@@ -55,18 +55,20 @@ enum charls_jpegls_errc
     CHARLS_JPEGLS_ERRC_UNEXPECTED_RESTART_MARKER = 22,
     CHARLS_JPEGLS_ERRC_RESTART_MARKER_NOT_FOUND = 23,
     CHARLS_JPEGLS_ERRC_END_OF_IMAGE_MARKER_NOT_FOUND = 24,
-    CHARLS_JPEGLS_ERRC_UNKNOWN_COMPONENT_ID = 25,
-    CHARLS_JPEGLS_ERRC_ABBREVIATED_FORMAT_AND_SPIFF_HEADER_MISMATCH = 26,
-    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_WIDTH = 27,
-    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_HEIGHT = 28,
-    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_BITS_PER_SAMPLE = 29,
-    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_COMPONENT_COUNT = 30,
-    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_INTERLEAVE_MODE = 31,
-    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_NEAR_LOSSLESS = 32,
-    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_JPEGLS_PRESET_PARAMETERS = 33,
-    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_COLOR_TRANSFORMATION = 34,
-    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_MAPPING_TABLE_ID = 35,
-    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_MAPPING_TABLE_CONTINUATION = 36,
+    CHARLS_JPEGLS_ERRC_UNEXPECTED_DEFINE_NUMBER_OF_LINES_MARKER = 25,
+    CHARLS_JPEGLS_ERRC_DEFINE_NUMBER_OF_LINES_MARKER_NOT_FOUND = 26,
+    CHARLS_JPEGLS_ERRC_UNKNOWN_COMPONENT_ID = 27,
+    CHARLS_JPEGLS_ERRC_ABBREVIATED_FORMAT_AND_SPIFF_HEADER_MISMATCH = 28,
+    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_WIDTH = 29,
+    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_HEIGHT = 30,
+    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_BITS_PER_SAMPLE = 31,
+    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_COMPONENT_COUNT = 32,
+    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_INTERLEAVE_MODE = 33,
+    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_NEAR_LOSSLESS = 34,
+    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_JPEGLS_PRESET_PARAMETERS = 35,
+    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_COLOR_TRANSFORMATION = 36,
+    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_MAPPING_TABLE_ID = 37,
+    CHARLS_JPEGLS_ERRC_INVALID_PARAMETER_MAPPING_TABLE_CONTINUATION = 38,
 
     // Logic errors:
 
@@ -270,9 +272,9 @@ enum class [[nodiscard]] jpegls_errc
     unknown_jpeg_marker_found = impl::CHARLS_JPEGLS_ERRC_UNKNOWN_JPEG_MARKER_FOUND,
 
     /// <summary>
-    /// This error is returned when a JPEG marker is found that is not valid for the current state.
+    /// This error is returned when the stream contains an unexpected SOS marker.
     /// </summary>
-    unexpected_marker_found = impl::CHARLS_JPEGLS_ERRC_UNEXPECTED_MARKER_FOUND,
+    unexpected_start_of_scan_marker = impl::CHARLS_JPEGLS_ERRC_UNEXPECTED_START_OF_SCAN_MARKER,
 
     /// <summary>
     /// This error is returned when the segment size of a marker segment is invalid.
@@ -325,6 +327,16 @@ enum class [[nodiscard]] jpegls_errc
     /// </summary>
     end_of_image_marker_not_found = impl::CHARLS_JPEGLS_ERRC_END_OF_IMAGE_MARKER_NOT_FOUND,
 
+    /// <summary>
+    /// This error is returned when the stream contains an unexpected DefineNumberOfLines (DNL) marker.
+    /// </summary>
+    unexpected_define_number_of_lines_marker = impl::CHARLS_JPEGLS_ERRC_UNEXPECTED_DEFINE_NUMBER_OF_LINES_MARKER,
+
+    /// <summary>
+    /// This error is returned when the DefineNumberOfLines (DNL) marker could not be found.
+    /// </summary>
+    define_number_of_lines_marker_not_found = impl::CHARLS_JPEGLS_ERRC_DEFINE_NUMBER_OF_LINES_MARKER_NOT_FOUND,
+
     /// <summary>
     /// This error is returned when an unknown component ID in a scan is detected.
     /// </summary>

src/jpeg_stream_reader.cpp

@@ -133,6 +133,12 @@ void jpeg_stream_reader::read_header(spiff_header* header, bool* spiff_header_fo
 
         if (state_ == state::bit_stream_section)
         {
+            if (frame_info_.height == 0)
+            {
+                find_and_read_define_number_of_lines_segment();
+            }
+
+            check_width();
             check_coding_parameters();
             return;
         }
@@ -197,7 +203,7 @@ void jpeg_stream_reader::validate_marker_code(const jpeg_marker_code marker_code
     {
     case jpeg_marker_code::start_of_scan:
         if (UNLIKELY(state_ != state::scan_section))
-            throw_jpegls_error(jpegls_errc::unexpected_marker_found);
+            throw_jpegls_error(jpegls_errc::unexpected_start_of_scan_marker);
 
         return;
 
@@ -228,8 +234,11 @@ void jpeg_stream_reader::validate_marker_code(const jpeg_marker_code marker_code
     case jpeg_marker_code::application_data15:
         return;
 
-    case jpeg_marker_code::define_number_of_lines: // DLN is a JPEG-LS valid marker, but not supported: handle as unknown.
-        throw_jpegls_error(jpegls_errc::unknown_jpeg_marker_found);
+    case jpeg_marker_code::define_number_of_lines:
+        if (!dnl_marker_expected_)
+            throw_jpegls_error(jpegls_errc::unexpected_define_number_of_lines_marker);
+
+        break;
 
     case jpeg_marker_code::start_of_image:
         throw_jpegls_error(jpegls_errc::duplicate_start_of_image_marker);
@@ -301,7 +310,6 @@ void jpeg_stream_reader::read_marker_segment(const jpeg_marker_code marker_code,
         break;
 
     case jpeg_marker_code::start_of_scan:
-        check_height_and_width();
         read_start_of_scan_segment();
         break;
 
@@ -313,6 +321,11 @@ void jpeg_stream_reader::read_marker_segment(const jpeg_marker_code marker_code,
         read_define_restart_interval_segment();
         break;
 
+    case jpeg_marker_code::define_number_of_lines:
+        read_define_number_of_lines_segment();
+        dnl_marker_expected_ = false;
+        break;
+
     case jpeg_marker_code::application_data8:
         try_read_application_data8_segment(header, spiff_header_found);
         break;
@@ -372,7 +385,7 @@ void jpeg_stream_reader::read_start_of_frame_segment()
                  frame_info_.bits_per_sample > maximum_bits_per_sample))
         throw_jpegls_error(jpegls_errc::invalid_parameter_bits_per_sample);
 
-    frame_info_height(read_uint16());
+    frame_info_height(read_uint16(), false);
     frame_info_width(read_uint16());
 
     frame_info_.component_count = read_uint8();
@@ -414,6 +427,13 @@ void jpeg_stream_reader::read_application_data_segment(const jpeg_marker_code ma
 }
 
 
+void jpeg_stream_reader::read_define_number_of_lines_segment()
+{
+    check_segment_size(2);
+    frame_info_height(read_uint16(), true);
+}
+
+
 void jpeg_stream_reader::read_preset_parameters_segment()
 {
     check_minimal_segment_size(1);
@@ -490,7 +510,7 @@ void jpeg_stream_reader::read_oversize_image_dimension()
         throw_jpegls_error(jpegls_errc::invalid_parameter_jpegls_preset_parameters);
     }
 
-    frame_info_height(height);
+    frame_info_height(height, false);
     frame_info_width(width);
 }
 
@@ -798,11 +818,8 @@ void jpeg_stream_reader::skip_remaining_segment_data() noexcept
 }
 
 
-void jpeg_stream_reader::check_height_and_width() const
+void jpeg_stream_reader::check_width() const
 {
-    if (UNLIKELY(frame_info_.height < 1))
-        throw_jpegls_error(jpegls_errc::parameter_value_not_supported);
-
     if (UNLIKELY(frame_info_.width < 1))
         throw_jpegls_error(jpegls_errc::invalid_parameter_width);
 }
@@ -815,12 +832,12 @@ void jpeg_stream_reader::check_coding_parameters() const
 }
 
 
-void jpeg_stream_reader::frame_info_height(const uint32_t height)
+void jpeg_stream_reader::frame_info_height(const uint32_t height, const bool final_update)
 {
-    if (height == 0)
+    if (height == 0 && !final_update)
         return;
 
-    if (UNLIKELY(frame_info_.height != 0))
+    if (UNLIKELY(frame_info_.height != 0 || height == 0))
         throw_jpegls_error(jpegls_errc::invalid_parameter_height);
 
     frame_info_.height = height;
@@ -849,6 +866,34 @@ void jpeg_stream_reader::call_application_data_callback(const jpeg_marker_code m
 }
 
 
+void jpeg_stream_reader::find_and_read_define_number_of_lines_segment()
+{
+    for (auto position{position_}; position < end_position_ - 1; ++position)
+    {
+        if (*position != jpeg_marker_start_byte)
+            continue;
+
+        const byte optional_marker_code{*(position + 1)};
+        if (optional_marker_code < byte{128} || optional_marker_code == jpeg_marker_start_byte)
+            continue;
+
+        // Found a marker, ISO / IEC 10918 - 1 B .2.5 requires that if DNL is used it must be at the end of the first scan.
+        if (static_cast<jpeg_marker_code>(optional_marker_code) != jpeg_marker_code::define_number_of_lines)
+            break;
+
+        const auto current_position{position_};
+        position_ = position + 2;
+        read_segment_size();
+        read_define_number_of_lines_segment();
+        dnl_marker_expected_ = true;
+        position_ = current_position;
+        return;
+    }
+
+    throw_jpegls_error(jpegls_errc::define_number_of_lines_marker_not_found);
+}
+
+
 void jpeg_stream_reader::add_mapping_table(const uint8_t table_id, const uint8_t entry_size,
                                            const span<const byte> table_data)
 {

src/jpeg_stream_reader.hpp

@@ -158,6 +158,7 @@ class jpeg_stream_reader final
     void read_start_of_scan_segment();
     void read_comment_segment();
     void read_application_data_segment(jpeg_marker_code marker_code);
+    void read_define_number_of_lines_segment();
     void read_preset_parameters_segment();
     void read_preset_coding_parameters();
     void read_oversize_image_dimension();
@@ -173,10 +174,11 @@ class jpeg_stream_reader final
     [[nodiscard]]
     uint32_t maximum_sample_value() const noexcept;
 
+    void find_and_read_define_number_of_lines_segment();
     void skip_remaining_segment_data() noexcept;
-    void check_height_and_width() const;
+    void check_width() const;
     void check_coding_parameters() const;
-    void frame_info_height(uint32_t height);
+    void frame_info_height(uint32_t height, bool final_update);
     void frame_info_width(uint32_t width);
     void call_application_data_callback(jpeg_marker_code marker_code) const;
     void add_mapping_table(uint8_t table_id, uint8_t entry_size, span<const std::byte> table_data);
@@ -284,6 +286,7 @@ class jpeg_stream_reader final
     std::vector<scan_info> scan_infos_;
     std::vector<mapping_table_entry> mapping_tables_;
     state state_{};
+    bool dnl_marker_expected_{};
     charls::compressed_data_format compressed_data_format_{};
     callback_function<at_comment_handler> at_comment_callback_{};
     callback_function<at_application_data_handler> at_application_data_callback_{};

src/jpegls_error.cpp

@@ -84,8 +84,8 @@ const char* CHARLS_API_CALLING_CONVENTION charls_get_error_message(const charls_
     case jpegls_errc::unknown_jpeg_marker_found:
         return "Invalid JPEG-LS stream: an unknown JPEG marker code was found";
 
-    case jpegls_errc::unexpected_marker_found:
-        return "Invalid JPEG-LS stream: unexpected marker found";
+    case jpegls_errc::unexpected_start_of_scan_marker:
+        return "Invalid JPEG-LS stream: unexpected Start Of Scan (SOS) marker found";
 
     case jpegls_errc::invalid_marker_segment_size:
         return "Invalid JPEG-LS stream: segment size of a marker segment is invalid";
@@ -117,6 +117,12 @@ const char* CHARLS_API_CALLING_CONVENTION charls_get_error_message(const charls_
     case jpegls_errc::end_of_image_marker_not_found:
         return "Invalid JPEG-LS stream: missing End Of Image (EOI) marker";
 
+    case jpegls_errc::unexpected_define_number_of_lines_marker:
+        return "Invalid JPEG-LS stream: unexpected Define Number of Lines (DNL) marker";
+
+    case jpegls_errc::define_number_of_lines_marker_not_found:
+        return "Invalid JPEG-LS stream: missing expected Define Number of Lines (DNL) marker";
+
     case jpegls_errc::unknown_component_id:
         return "Invalid JPEG-LS stream: unknown component ID in scan segment";