Image Processing

Use Image Processing to perform a number of actions on images. The tool lets you align, threshold, scale, and crop images. You can also balance their brightness and convert them to grayscale.

Tool Components

Image Processing has 2 anchors:

• Input anchor: Use the input anchor to connect to the data that contains the images you want to process.
• Output anchor: Use the output anchor to pass processed images downstream.

Configure the Tool

1. Add Image Processing to the canvas.
2. Use the input anchor to connect the tool to the data that contains the images you want to process.
3. From the Image field, select the images you want to process.
4. Select the Add Step button to open a dropdown that allows you to add any of these steps:
   • Alignment
   • Thresholding
   • Scale
   • Crop
   • Brightness Balance
   • Grayscale
     
     The tool processes each step in order from top to bottom. You can drag steps you've already added to reorder them. Select the thrash-can icons to remove steps.
5. Run the workflow.

Advanced

Each step of the image processing has advanced configuration options.

Alignment

Automatically or manually rotate images. The Auto option to allows the tool to automatically align images. If you choose the Custom option, you can use the slider to specify the degree and direction of the rotation that the tool applies to images. Select the refresh icon to reset the slider.

Thresholding

Set a threshold to convert images to a binary, like black and white, for each channel.

We provide a several algorithms you can use to threshold your images. In most cases, we recommend that you use Adaptive Gaussian for images of text, like scanned pages of a book, and Binary for other images, like photographs. For a more in-depth discussion of thresholding, visit OpenCV's thresholding documentation.

Note—Adaptive thresholding methods require images to be single channel (in other words, grayscale). If you don't have a Grayscale step preceding a Thresholding step, we perform grayscaling for you, but we don't asdd a grayscale step in the Configuration window.

Scale

Resize images.

Choose how much bigger or smaller you want to make the images. You can specify the width and height in pixels or by percentage relative to the size of the original images.

You can also choose to lock the aspect ratio of your images, which means that their proportions won't change even if you change the height or width.

Crop

Remove parts of images.

To crop an image, choose how much of the image you want to keep. You can make that selection by indicating the width and height in pixels or percentages. Then use the anchor grid to select what portion of the image you want to keep after cropping.

Brightness Balance

Automatically or manually adjust the brightness of images.

Convert multi-channel images to single channel. The Auto option allows the tool to automatically balance the brightness of images. If you select the Custom option, you can use the slider specify how light or dark you want the image to be.

Grayscale

Convert multi-channel images to single channel. You don't have to configure anything.