Simplifying chroma subsample

codecs/mozjpeg_enc/README.md

@@ -39,6 +39,9 @@ struct MozJpegOptions {
   bool trellis_opt_zero;
   bool trellis_opt_table;
   int trellis_loops;
+  bool auto_subsample;
   int chroma_subsample;
+  bool separate_chroma_quality;
+  int chroma_quality;
 };
 ```

codecs/mozjpeg_enc/example.html

@@ -33,7 +33,8 @@
       trellis_opt_zero: false,
       trellis_opt_table: false,
       trellis_loops: 1,
-      chroma_subsample: 0,
+      auto_subsample: true,
+      chroma_subsample: 2,
       separate_chroma_quality: false,
       chroma_quality: 75,
     });

codecs/mozjpeg_enc/mozjpeg_enc.cpp

@@ -29,6 +29,7 @@ struct MozJpegOptions {
   bool trellis_opt_zero;
   bool trellis_opt_table;
   int trellis_loops;
+  bool auto_subsample;
   int chroma_subsample;
   bool separate_chroma_quality;
   int chroma_quality;
@@ -152,7 +153,7 @@ val encode(std::string image_in, int image_width, int image_height, MozJpegOptio
 
   set_quality_ratings(&cinfo, (char*) pqual, opts.baseline);
 
-  if (opts.chroma_subsample && opts.color_space == JCS_YCbCr) {
+  if (!opts.auto_subsample && opts.color_space == JCS_YCbCr) {
     cinfo.comp_info[0].h_samp_factor = opts.chroma_subsample;
     cinfo.comp_info[0].v_samp_factor = opts.chroma_subsample;
   }
@@ -220,6 +221,7 @@ EMSCRIPTEN_BINDINGS(my_module) {
     .field("trellis_opt_table", &MozJpegOptions::trellis_opt_table)
     .field("trellis_loops", &MozJpegOptions::trellis_loops)
     .field("chroma_subsample", &MozJpegOptions::chroma_subsample)
+    .field("auto_subsample", &MozJpegOptions::auto_subsample)
     .field("separate_chroma_quality", &MozJpegOptions::separate_chroma_quality)
     .field("chroma_quality", &MozJpegOptions::chroma_quality)
     ;

src/codecs/mozjpeg/encoder-meta.ts

@@ -17,6 +17,7 @@ export interface EncodeOptions {
   trellis_opt_zero: boolean;
   trellis_opt_table: boolean;
   trellis_loops: number;
+  auto_subsample: boolean;
   chroma_subsample: number;
   separate_chroma_quality: boolean;
   chroma_quality: number;
@@ -41,7 +42,8 @@ export const defaultOptions: EncodeOptions = {
   trellis_opt_zero: false,
   trellis_opt_table: false,
   trellis_loops: 1,
-  chroma_subsample: 0,
+  auto_subsample: true,
+  chroma_subsample: 2,
   separate_chroma_quality: false,
   chroma_quality: 75,
 };

src/codecs/mozjpeg/options.tsx

@@ -39,19 +39,17 @@ export default class MozJPEGEncoderOptions extends Component<Props, State> {
       trellis_multipass: inputFieldChecked(form.trellis_multipass, options.trellis_multipass),
       trellis_opt_zero: inputFieldChecked(form.trellis_opt_zero, options.trellis_opt_zero),
       trellis_opt_table: inputFieldChecked(form.trellis_opt_table, options.trellis_opt_table),
+      auto_subsample: inputFieldChecked(form.auto_subsample, options.auto_subsample),
       separate_chroma_quality:
         inputFieldChecked(form.separate_chroma_quality, options.separate_chroma_quality),
       // .value
       quality: inputFieldValueAsNumber(form.quality, options.quality),
       chroma_quality: inputFieldValueAsNumber(form.chroma_quality, options.chroma_quality),
+      chroma_subsample: inputFieldValueAsNumber(form.chroma_subsample, options.chroma_subsample),
       smoothing: inputFieldValueAsNumber(form.smoothing, options.smoothing),
       color_space: inputFieldValueAsNumber(form.color_space, options.color_space),
       quant_table: inputFieldValueAsNumber(form.quant_table, options.quant_table),
       trellis_loops: inputFieldValueAsNumber(form.trellis_loops, options.trellis_loops),
-      // Other:
-      chroma_subsample: (!form.auto_chroma_subsample) ? options.chroma_subsample :
-        form.auto_chroma_subsample.checked ? 0 :
-        inputFieldValueAsNumber(form.chroma_subsample, 2),
     };
     this.props.onChange(newOptions);
   }
@@ -99,14 +97,14 @@ export default class MozJPEGEncoderOptions extends Component<Props, State> {
                   <div>
                     <label class={style.optionInputFirst}>
                       <Checkbox
-                        name="auto_chroma_subsample"
-                        checked={options.chroma_subsample === 0}
+                        name="auto_subsample"
+                        checked={options.auto_subsample}
                         onChange={this.onChange}
                       />
                       Auto subsample chroma
                     </label>
                     <Expander>
-                      {options.chroma_subsample !== 0 ?
+                      {options.auto_subsample ? null :
                         <div class={style.optionOneCell}>
                           <Range
                             name="chroma_subsample"
@@ -118,7 +116,6 @@ export default class MozJPEGEncoderOptions extends Component<Props, State> {
                             Subsample chroma by:
                           </Range>
                         </div>
-                        : null
                       }
                     </Expander>
                     <label class={style.optionInputFirst}>