@vladmandic/face-api/build/src/ops/padToSquare.js

JavaScript module for Face Detection and Face Recognition Using Tensorflow/JS

import * as tf from '@tensorflow/tfjs/dist/tf.es2017.js';
/**
 * Pads the smaller dimension of an image tensor with zeros, such that width === height.
 *
 * @param imgTensor The image tensor.
 * @param isCenterImage (optional, default: false) If true, add an equal amount of padding on
 * both sides of the minor dimension oof the image.
 * @returns The padded tensor with width === height.
 */
export function padToSquare(imgTensor, isCenterImage = false) {
    return tf.tidy(() => {
        const [height, width] = imgTensor.shape.slice(1);
        if (height === width) {
            return imgTensor;
        }
        const dimDiff = Math.abs(height - width);
        const paddingAmount = Math.round(dimDiff * (isCenterImage ? 0.5 : 1));
        const paddingAxis = height > width ? 2 : 1;
        const createPaddingTensor = (paddingAmount) => {
            const paddingTensorShape = imgTensor.shape.slice();
            paddingTensorShape[paddingAxis] = paddingAmount;
            return tf.fill(paddingTensorShape, 0, 'float32');
        };
        const paddingTensorAppend = createPaddingTensor(paddingAmount);
        const remainingPaddingAmount = dimDiff - paddingTensorAppend.shape[paddingAxis];
        const paddingTensorPrepend = isCenterImage && remainingPaddingAmount
            ? createPaddingTensor(remainingPaddingAmount)
            : null;
        const tensorsToStack = [
            paddingTensorPrepend,
            imgTensor,
            paddingTensorAppend
        ]
            .filter(t => !!t)
            // .map((t: tf.Tensor) => t.toFloat()) as tf.Tensor4D[]
            .map((t) => tf.cast(t, 'float32'));
        return tf.concat(tensorsToStack, paddingAxis);
    });
}
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