This is where things begin to get exciting. We now have master images for each filter. With linear image processing, we do the initial cleanup before stretching the image.

The first step is to do a dynamic crop to remove any black edges due to field rotation during image integration. To do this properly, you need to make sure that all master images are aligned.

NOTE: If not, you will need to run star alignment (without drizzle and local normalization) on the master images.

Dynamic Crop Settings

Dynamic crop is easy to do.

  • First, open all master images within PixInsight and launch the dynamic crop process.
  • Hit reset within the dynamic crop process. One of the images should now have an opaque box round the image. Drag the edges and rotate as needed to get the right cropping dimension.
  • Within the dynamic crop process, drag the triangle (New Instance) onto an empty part of the PixInsight workspace. This will create a new instance of the dynamic crop process with identity settings.
  • Select the green check mark to execute. Verify that the crop is what you wanted.
  • Close the dynamic crop tool
  • Select another image and launch the dynamic crop instance you previously created. A crop box will appear with the same dimensions as the first crop. Select the green check mark to execute. Close the crop tool.
  • Repeat process for all images.
  • Save images

What’s Next

Once the images are cropped, it is time to remove any background gradients with the Dynamic Background Extraction tool.