Adding easier to use interface for blend module and different blend modes (#1453)

* Bump data-uri-to-buffer from 2.0.1 to 3.0.0

Bumps [data-uri-to-buffer](https://github.com/TooTallNate/node-data-uri-to-buffer) from 2.0.1 to 3.0.0.
- [Release notes](https://github.com/TooTallNate/node-data-uri-to-buffer/releases)
- [Commits](https://github.com/TooTallNate/node-data-uri-to-buffer/compare/2.0.1...3.0.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

* add blend modes

* fix toCliString test

* add docs link for blend modes

* fix crop module

* undo last commit

* minor change

* change default to custom

* add docs link

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>
Co-authored-by: Harsh Khandeparkar <34770591+HarshKhandeparkar@users.noreply.github.com>
Co-authored-by: Jeffrey Warren <jeff@unterbahn.com>

docs/MODULES.md

@@ -78,7 +78,8 @@ This module is used for averaging all the pixels of the image.
 
 ## blend-module
 
-This module is used for blending two images .
+This module is used for blending two images. For More info read:  _[wiki](https://en.wikipedia.org/wiki/Blend_modes)_
+
 #### Usage
 
 ```js
@@ -88,8 +89,12 @@ This module is used for blending two images .
 ```
 
 where `options` is an object with the following properties:
-* offset: step of image with which current image is to be blended(Two steps back is -2, three                steps back is -3 etc; default -2) 
-* func: function used to blend two images (default : function(r1, g1, b1, a1, r2, g2, b2, a2) {            return [ r1, g2, b2, a2 ] })
+* offset: step of image with which current image is to be blended(Two steps back is -2, three steps back is -3 etc; default -2) 
+* blendMode: Blending mode to use for blending two images by default it uses the given function
+* func: function used to blend two images (default : function(r1, g1, b1, a1, r2, g2, b2, a2) { return [ r1, g2, b2, a2 ] })
+
+[More info for different blend modes can be found here](http://docs.gimp.org/en/gimp-concepts-layer-modes.html)
+
 
 ## Blob Analysis
 

src/modules/Blend/Module.js

@@ -4,6 +4,7 @@ module.exports = function Blend(options, UI, util) {
 
   options.func = options.blend || defaults.blend;
   options.offset = options.offset || defaults.offset;
+  options.blendMode = options.blendMode || defaults.blendMode;
 
   var output;
 
@@ -29,22 +30,79 @@ module.exports = function Blend(options, UI, util) {
       callback();
     }
 
+    // see http://docs.gimp.org/en/gimp-concepts-layer-modes.html for other blend modes
+
+    const multiply_mode = function (i, m) {
+      return ~~( (i * m) / 255 );
+    };
+    const divide_mode = function (i, m) {
+      return ~~( (256 * i) / (m + 1) );
+    };
+
+    const overlay_mode = function (i, m) {
+      return ~~( (i / 255) * (i + ((2 * m) / 255) * (255 - i)) );
+    };
+    
+    const screen_mode = function (i, m) {
+      return ~~( 255 - ((255 - m) * (255 - i)) / 255 );
+    };
+    
+    const sof_light_mode = function (i, m) {
+      var Rs = screen_mode(i, m);
+      return ~~( ((((255 - i) * m) + Rs) * i) / 255 );
+    };
+    
+    const color_dodge = function (i, m) {
+      return ~~( (256 * i) / (255 - m + 1) );
+    };
+
+    const burn_mode = function (i, m) {
+      return ~~( 255 - (256 * (255 - i)) / (m + 1));
+    };
+
+    const grain_extract_mode = function (i, m) {
+      return ~~( i - m + 128 );
+    };
+
+    const grain_merge_mode = function (i, m) {
+      return ~~( i + m - 128 );
+    };
+
+    
     getPixels(priorStep.output.src, function(err, pixels) {
       options.firstImagePixels = pixels;
+
       // Convert to runnable code.
       if (typeof options.func === 'string') eval('options.func = ' + options.func);
+      
       function changePixel(r2, g2, b2, a2, x, y) {
         // blend!
         let p = options.firstImagePixels;
-        return options.func(
-          r2, g2, b2, a2,
-          p.get(x, y, 0),
-          p.get(x, y, 1),
-          p.get(x, y, 2),
-          p.get(x, y, 3),
-          x,
-          y
-        );
+        let r1 = p.get(x, y, 0),
+          g1 = p.get(x, y, 1),
+          b1 = p.get(x, y, 2),
+          a1 = p.get(x, y, 3);
+
+        const blends = {
+          'Color Dodge': () => [color_dodge(r2, r1), color_dodge(g2, g1), color_dodge(b2, b1), 255],
+          'Multiply': () => [multiply_mode(r2, r1), multiply_mode(g2, g1), multiply_mode(b2, b1), multiply_mode(a2, a1)],
+          'Divide': () => [divide_mode(r2, r1), divide_mode(g2, g1), divide_mode(b2, b1), 255],
+          'Overlay': () => [overlay_mode(r2, r1), overlay_mode(g2, g1), overlay_mode(b2, b1), 255],
+          'Screen': () => [screen_mode(r2, r1), screen_mode(g2, g1), screen_mode(b2, b1), 255],
+          'Soft Light': () => [sof_light_mode(r2, r1), sof_light_mode(g2, g1), sof_light_mode(b2, b1), 255],
+          'Color Burn': () => [burn_mode(r2, r1), burn_mode(g2, g1), burn_mode(b2, b1), 255],
+          'Grain Extract': () => [grain_extract_mode(r2, r1), grain_extract_mode(g2, g1), grain_extract_mode(b2, b1), 255],
+          'Grain Merge': () => [grain_merge_mode(r2, r1), grain_merge_mode(g2, g1), grain_merge_mode(b2, b1), 255]
+        };
+        
+        if(options.blendMode == 'custom')
+          return options.func(
+            r2, g2, b2, a2, r1, g1, b1, a1
+          );
+        else {
+          return blends[options.blendMode]();
+        }
+
       }
 
       function output(image, datauri, mimetype, wasmSuccess) {

src/modules/Blend/info.json

@@ -1,17 +1,34 @@
 {
   "name": "blend",
-  "description": "Blend two chosen image steps with the given function. Defaults to using the red channel from image 1 and the green and blue and alpha channels of image 2. Easier to use interfaces coming soon!",
+  "description": "Blend two chosen image steps with the given function. Defaults to using the red channel from image 1 and the green and blue and alpha channels of image 2.",
   "inputs": {
     "offset": {
       "type": "integer",
       "desc": "Choose which image to blend the current image with. Two steps back is -2, three steps back is -3 etc.",
       "default": -2
     },
+    "blendMode": {
+      "type": "select",
+      "desc": "Name of the Blend Mode to use",
+      "default": "custom",
+      "values": [
+        "custom",
+        "Multiply",
+        "Divide",
+        "Overlay",
+        "Screen",
+        "Soft Light",
+        "Color Burn",
+        "Color Dodge",
+        "Grain Extract",
+        "Grain Merge"
+      ]
+    },
     "blend": {
       "type": "string",
       "desc": "Function to use to blend the two images.",
       "default": "function(r1, g1, b1, a1, r2, g2, b2, a2, x, y) { return [ r2, g2, b2, a2 ] }"
     }
   },
-  "docs-link":"https://github.com/publiclab/image-sequencer/blob/main/docs/MODULES.md#blend-module"
+  "docs-link": "https://github.com/publiclab/image-sequencer/blob/main/docs/MODULES.md#blend-module"
 }

test/core/sequencer/image-sequencer.js

@@ -192,7 +192,7 @@ test('getStep(offset) returns the step at offset distance relative to current st
 });
 
 test('toCliString() returns the CLI command for the sequence', function(t) {
-  t.deepEqual(sequencer.toCliString(), 'sequencer -i [PATH] -s "channel channel channel channel invert brightness average brightness invert blend" -d \'{"channel":"green","brightness":"1","offset":-2}\'', 'works correctly');
+  t.deepEqual(sequencer.toCliString(), 'sequencer -i [PATH] -s "channel channel channel channel invert brightness average brightness invert blend" -d \'{"channel":"green","brightness":"1","offset":-2,"blendMode":"custom"}\'', 'works correctly');
   t.end();
 });