Initial Slow Version of Blurring Backgrounds with Bodypix

decode_image/LICENSE

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+MIT License
+
+Copyright (c) 2020 Daniel Llewellyn
+Copyright (c) 2020 Benjamin Elder
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

decode_image/index.js

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+const {Tensor3D, tensor3d, util} = require('@tensorflow/tfjs-core');
+const jpeg = require('jpeg-js');
+
+/**
+ * Decode a JPEG-encoded image to a 3D Tensor of dtype `int32`.
+ *
+ * ```js
+ * const image = require('path/to/img.jpg');
+ * const imageAssetPath = Image.resolveAssetSource(image);
+ * const response = await fetch(imageAssetPath.uri, {}, { isBinary: true });
+ * const rawImageData = await response.arrayBuffer();
+ * const imageTensor = decodeJpeg(rawImageData);
+ * ```
+ *
+ * @param contents The JPEG-encoded image in an Uint8Array.
+ * @param channels An optional int. Defaults to 3. Accepted values are
+ *     0: use the number of channels in the JPG-encoded image.
+ *     1: output a grayscale image.
+ *     3: output an RGB image.
+ * @returns A 3D Tensor of dtype `int32` with shape [height, width, 1/3].
+ */
+/** @doc {heading: 'Media', subheading: 'Images'} */
+function decodeJpeg(
+    contents, channels = 3) {
+  util.assert(
+      getImageType(contents) === 'jpeg',
+      () => 'The passed contents are not a valid JPEG image');
+  util.assert(
+      channels === 3, () => 'Only 3 channels is supported at this time');
+  const TO_UINT8ARRAY = true;
+  const {width, height, data} = jpeg.decode(contents, TO_UINT8ARRAY);
+  // Drop the alpha channel info because jpeg.decode always returns a typedArray
+  // with 255
+  const buffer = new Uint8Array(width * height * 3);
+  let offset = 0;  // offset into original data
+  for (let i = 0; i < buffer.length; i += 3) {
+    buffer[i] = data[offset];
+    buffer[i + 1] = data[offset + 1];
+    buffer[i + 2] = data[offset + 2];
+
+    offset += 4;
+  }
+
+  return tensor3d(buffer, [height, width, channels]);
+}
+
+/**
+ * Helper function to get image type based on starting bytes of the image file.
+ */
+function getImageType(content) {
+  // Classify the contents of a file based on starting bytes (aka magic number:
+  // tslint:disable-next-line:max-line-length
+  // https://en.wikipedia.org/wiki/Magic_number_(programming)#Magic_numbers_in_files)
+  // This aligns with TensorFlow Core code:
+  // tslint:disable-next-line:max-line-length
+  // https://github.com/tensorflow/tensorflow/blob/4213d5c1bd921f8d5b7b2dc4bbf1eea78d0b5258/tensorflow/core/kernels/decode_image_op.cc#L44
+  if (content.length > 3 && content[0] === 255 && content[1] === 216 &&
+      content[2] === 255) {
+    // JPEG byte chunk starts with `ff d8 ff`
+    return 'jpeg';
+  } else if (
+      content.length > 4 && content[0] === 71 && content[1] === 73 &&
+      content[2] === 70 && content[3] === 56) {
+    // GIF byte chunk starts with `47 49 46 38`
+    return 'gif';
+  } else if (
+      content.length > 8 && content[0] === 137 && content[1] === 80 &&
+      content[2] === 78 && content[3] === 71 && content[4] === 13 &&
+      content[5] === 10 && content[6] === 26 && content[7] === 10) {
+    // PNG byte chunk starts with `\211 P N G \r \n \032 \n (89 50 4E 47 0D 0A
+    // 1A 0A)`
+    return 'png';
+  } else if (content.length > 3 && content[0] === 66 && content[1] === 77) {
+    // BMP byte chunk starts with `42 4d`
+    return 'bmp';
+  } else {
+    throw new Error(
+        'Expected image (JPEG, PNG, or GIF), but got unsupported image type');
+  }
+}
+
+module.exports = {
+  decodeJpeg
+}