Return :arw as format for Sony ARW files (#164)

Add detection for Sony ARW files and return :arw in the format property for those files.

Closes #159

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.24.0
+* The TIFF parser will now return :arw as format for Sony ARW files insted of :tif so that the caller can decide whether it
+  wants to deal with RAW processing or not
+
 ## 0.23.1
 * Updated gem exifr to fix problems related to jpeg files from Olympos microscopes, which often have bad thumbnail data
 

lib/format_parser/version.rb

@@ -1,3 +1,3 @@
 module FormatParser
-  VERSION = '0.23.1'
+  VERSION = '0.24.0'
 end

lib/parsers/tiff_parser.rb

@@ -26,7 +26,7 @@ def call(io)
     h = exif_data.height || exif_data.pixel_y_dimension
 
     FormatParser::Image.new(
-      format: :tif,
+      format: arw?(exif_data) ? :arw : :tif, # Specify format as arw for Sony ARW format images, else tif
       width_px: w,
       height_px: h,
       display_width_px: exif_data.rotated? ? h : w,
@@ -43,5 +43,11 @@ def cr2?(io)
     safe_read(io, 2) == 'CR'
   end
 
+  # Similar to how exiftool determines the image type as ARW, we are implementing a check here
+  # https://github.com/exiftool/exiftool/blob/e969456372fbaf4b980fea8bb094d71033ac8bf7/lib/Image/ExifTool/Exif.pm#L929
+  def arw?(exif_data)
+    exif_data.compression == 6 && exif_data.new_subfile_type == 1 && exif_data.make == 'SONY'
+  end
+
   FormatParser.register_parser new, natures: :image, formats: :tif
 end

spec/parsers/tiff_parser_spec.rb

@@ -47,12 +47,15 @@
     expect(parsed.intrinsics[:exif]).not_to be_nil
   end
 
-  it 'correctly extracts dimensions for a Sony ARW fixture' do
+  it 'parses Sony ARW fixture as arw format file' do
     arw_path = fixtures_dir + '/ARW/RAW_SONY_ILCE-7RM2.ARW'
 
     parsed = subject.call(File.open(arw_path, 'rb'))
 
     expect(parsed).not_to be_nil
+    expect(parsed.nature).to eq(:image)
+    expect(parsed.format).to eq(:arw)
+
     expect(parsed.width_px).to eq(7952)
     expect(parsed.height_px).to eq(5304)
     expect(parsed.intrinsics[:exif]).not_to be_nil