Gary Palmer
Last month we explained how to stack your solar captures; this month we’re going to turn them into a mosaic. Once all the images have been run through RegiStax you need to crop any stack lines from them – we’d recommend using the freeware Faststone Image Viewer (www.faststone.org) to do this. Crop each frame to leave neat edges. If you used different settings for your images of the Sun’s surface and its prominences, put them in separate folders.
Open Photoshop and click File > Scripts > Load Files into Stack. Select all of your mosaic surface images from the folder they have been saved in, and check the box to align images automatically. This process can take some time depending on the speed of your computer, but once complete you should have the mosaic all aligned with each image on a separate layer.
Next we need to adjust each layer with the Levels tool, as one of the problems with creating large solar mosaics is the difference in contrast between panes. Select each layer and click the Levels icon in the Image Adjustments palette. Adjust the middle slider on each pane to get the contrast as balanced as possible; once you are happy click Select > All Layers, then Edit > Auto Blend Layers. When the process has finished you might see some staggered lines – don’t worry about them. Right click on the layers and select Flatten Image. The image should now be complete, with no lines, ready for you to adjust sharpness and contrast.
For best results with the prominence images, align them manually. Open a prominence image in a new Photoshop window. Click Image > Canvas Size, select percentage, then type 400 for horizontal and vertical. Now you can drag and drop each prominence pane in to create the complete ring. As before, you will need to adjust the Levels to match the contrast between layers. Once done, select all the layers, auto blend and flatten as above.
Now we’ll add the two together. Go back to your surface image and select the Magic Wand tool (set tolerance to 10). Click Select > Inverse and copy the selection, then return to the prominence image and paste it in. The surface layer will be slight smaller than the prominence one. To adjust, select the surface layer and click Edit > Free Transform. Drag the image by the corners to fit the prominence ring. When you are happy, click the tick in the title bar. Right click on the layers and select Flatten to finish.