Overview

This article shows you how to do mosaics with Siril and Microsoft Image Composite Editor. I’m told that Siril 1.4 will contain mosaic features and some of them are present today, but they’re not quite ready for use. For now, we’ll prepare our frames in Siril and piece the mosaic together with Microsoft Image Composite Editor.

Stack Each Pane

The first thing to do is to separately stack each mosaic pane as you would do normally. It’s best to use the same equipment and stacking techniques on each pane. The critical thing is to keep each pane of the mosaic as similar as possible

Prepare Each Pane

Once you have each pane, you need to do the following to prepare :-

1. Plate solve to ensure that the pane is orientated consistently
2. If this is a colour frame, correct the colour, preferably using SPCC from Siril Alpha
3. Crop to remove any dithering artifacts crop 40 40 3790 2100
4. Remove any background gradient subsky -rbf -smooth=1 -dither
5. Do any noise reduction that you would like to do, but keep this the same between all frames. Personally, I use Graxpert here
6. Normalize the background level of each frame using pixelmath. Example below pm $o3-2_GraXpert$*mad($o3-1_GraXpert$)/mad($o3-2_GraXpert$)-mad($o3-1_GraXpert$)/mad($o3-2_GraXpert$)*median($o3-2_GraXpert$)+median($o3-1_GraXpert$)

Create the mosaic

1. Convert each frame to TIF. Load these into Microsoft Image Composite Editor to create your mosaic
2. Load the resulting mosaic into Siril and process as normal