Panoramas, HDR and image stacking in Paint by Zaweba
File > Automate in Paint by Zaweba builds panoramas, merges HDR with ghost removal, and stacks images, including astrophotography with calibration.
Some pictures can only be made from several photographs. A sweeping view wider than the lens, a scene too contrasty for one exposure, a night sky full of faint stars: each needs a batch of shots combined into one. Paint by Zaweba collects the tools for that under File > Automate, and they all run on your own computer, however large the files.
Panorama
Panorama stitches overlapping shots into one wide picture. It offers several layouts. Auto lets the app choose. Perspective suits flat subjects and smaller panoramas. Cylindrical suits wide horizontal views. Spherical suits very wide or tall views that cover a large part of the scene around you. Collage and reposition place the shots with simpler transforms, for flat subjects or shots that only shifted a little.
It also offers vignette removal, which evens out the darker corners many lenses produce so they don't show as dark bands at the joins, and distortion correction for lens bending. Smart Fill can fill the gaps at the edges that stitching leaves, so you can keep more of the frame instead of cropping tightly.
Merge to HDR
Merge to HDR combines bracketed exposures, typically one dark, one normal and one bright shot, into a single high dynamic range image that holds detail from the deepest shadow to the brightest highlight. Ghost removal handles things that moved between shots, such as people or branches, which would otherwise appear as see-through doubles.
The merged image can be saved as .hdr or .exr. Then use Tone Mapping in the app to turn it into a picture for screens and prints.
Image Stacking
Image Stacking combines a set of aligned shots of the same scene with a statistical method. The choices are mean, median, maximum, minimum, range, variance, standard deviation, summation, skewness, kurtosis and entropy.
Mean averages the frames, which reduces noise and gives a long-exposure look to moving water. Median takes the middle value for each pixel, which removes anything that appears in only a few frames: shoot a busy square from a tripod and median removes the people walking through. Maximum keeps the brightest value, which builds star trails or light trails from a series. Minimum keeps the darkest. The others are specialist tools for analysis and science work, showing where frames differ and by how much.
Load Files into Stack brings a folder of shots into one document as layers, which is the usual first step for stacking or for working with the Auto-Align and Auto-Blend tools.
Astrophotography Stacking
Astrophotography Stacking is built for the night sky. It combines many light frames of the same target and uses calibration masters: bias frames, which capture the sensor's base signal, dark frames, which capture its noise during long exposures, and flat frames, which capture dust and vignetting in the optics. Subtracting and dividing these out gives a much cleaner result than stacking alone. It also reads FITS files, the standard format of astronomy cameras.
Getting good source shots
For all of these, consistency matters. Use a tripod where you can, fix the exposure and white balance for panoramas and stacks, and take more frames than you think you need. For HDR, bracket in steps wide enough to cover the full range of the scene.
Shoot RAW if your camera allows. Develop all the frames the same way in the RAW Developer, so the merge starts from matched images.
After the merge
Merged images rarely come out finished. Crop or fill panorama edges, tone map HDR, and stretch the faint detail out of astronomical stacks with Curves and Levels. Paint by Zaweba has all of those tools in the same place, so you can go from a folder of frames to a finished picture without changing program.
