Continuing a thread started on Gitter:

Hello, I want to run a Tensorflow model I found with a Java app, but I am having difficulty with getting the input just right. Below you can see the result from the layer analysis. I found a few examples for one-dimensional input (mnist) and I got another model working that required integers, but creating Tensor with dimensions {batch, height, width, channels} is a difficult task. I would like some help. The input is just a JPG, basically BufferedImage as I want to keep my options open.

Often TF Java users are looking for a snippet showing how this can be done easily, Iâ€™m sharing one here written in Kotlin (warning, I did not test it out after modifying it, but basically the logic should be good):

```
fun preprocess(sourceImages: List<BufferedImage>, imageHeight: Int, imageWidth: Int, imageChannels: Int): TFloat32 {
val imageShape = Shape.of(sourceImages.size.toLong(), imageHeight.toLong(), imageWidth.toLong(), imageChannels.toLong())
return TFloat32.tensorOf(imageShape) { tensor ->
// Copy all images to the tensor
sourceImages.forEachIndexed { imageIdx, sourceImage ->
// Scale the image to required dimensions if needed
val image = if (sourceImage.width != imageWidth || sourceImage.height != imageHeight) {
val scaledImage = BufferedImage(imageWidth, imageHeight, BufferedImage.TYPE_3BYTE_BGR)
scaledImage.createGraphics().apply {
setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR)
drawImage(sourceImage, 0, 0, imageWidth, imageHeight, null)
dispose()
}
scaledImage
} else {
sourceImage
}
// Converts the image to floats and normalize by subtracting mean values
var i = 0
for (h in 0L until imageHeight) {
for (w in 0L until imageWidth) {
// "caffe"-style normalization
tensor.setFloat(image.data.dataBuffer.getElemFloat(i++) - 103.939f, imageIdx.toLong(), h, w, 0)
tensor.setFloat(image.data.dataBuffer.getElemFloat(i++) - 116.779f, imageIdx.toLong(), h, w, 1)
tensor.setFloat(image.data.dataBuffer.getElemFloat(i++) - 123.68f, imageIdx.toLong(), h, w, 2)
}
}
}
}
}
```

So the idea is simply to resample your image if it is not already of the right size and to normalize its pixel values when feeding the tensor. The â€ścaffeâ€ť-style normalization is the one used by default by Keras in Python so the mean values to subtract were picked from Keras sources directly.

UPDATED : hereâ€™s the Java version

```
TFloat32 preprocess(List<BufferedImage> sourceImages, int imageHeight, int imageWidth, int imageChannels) {
Shape imageShape = Shape.of(sourceImages.size(), imageHeight, imageWidth, imageChannels);
return TFloat32.tensorOf(imageShape, tensor -> {
// Copy all images to the tensor
int imageIdx = 0;
for (BufferedImage sourceImage : sourceImages) {
// Scale the image to required dimensions if needed
BufferedImage image;
if (sourceImage.getWidth() != imageWidth || sourceImage.getHeight() != imageHeight) {
image = new BufferedImage(imageWidth, imageHeight, BufferedImage.TYPE_3BYTE_BGR);
Graphics2D graphics = image.createGraphics();
graphics.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR);
graphics.drawImage(sourceImage, 0, 0, imageWidth, imageHeight, null);
graphics.dispose();
} else {
image = sourceImage;
}
// Converts the image to floats and normalize by subtracting mean values
int i = 0;
for (long h = 0; h < imageHeight; ++h) {
for (long w = 0; w < imageWidth; ++w) {
// "caffe"-style normalization
tensor.setFloat(image.getData().getDataBuffer().getElemFloat(i++) - 103.939f, imageIdx, h, w, 0);
tensor.setFloat(image.getData().getDataBuffer().getElemFloat(i++) - 116.779f, imageIdx, h, w, 1);
tensor.setFloat(image.getData().getDataBuffer().getElemFloat(i++) - 123.68f, imageIdx, h, w, 2);
}
}
++imageIdx;
}
});
}
```