Image alignment, also known as image registration, is the process of overlaying images and shifting them as necessary to ensure that features in the images line up at the same pixel coordinates. Images need to be in alignment before image stacking can be performed on them.
Chasys Draw IES allows for both manual and automated alignment, with the option to fine-tune the calculated layer offsets.
The “how” bit
You need at least 2 same-size images of the same scene to run this engine.
This is the GUI for aligning the images:
The first layer is used as the reference, and always has the offsets (0,0). All other layers are aligned against this layer, with offsets specified in pixels. Chasys Draw IES can align the images for you based on reference points that you provide; you can also align the images manually. The following functions are supported:
Function
Description
Offsets
This command tells Chasys Draw IES to attempt to calculating the offsets of all layers automatically using its image registration algorithm. It uses the reference marked by the crosshairs. You are advised to double-check the results and use the refine option or make manual adjustments since the algorithm may make mistakes. Chasys Draw IES will use the selected reference point to do the calculation.
Rotation
This command tells Chasys Draw IES to attempt to calculating the rotations of all layers automatically using its image registration algorithm. It uses two references; the reference marked by the crosshairs for the center of rotation and the reference marked by the diagonal crosshairs for the actual rotation. You are advised to double-check the results and use the refine option or make manual adjustments since the algorithm may make mistakes. Chasys Draw IES will use the selected reference point to do the calculation.
Reset
This command sets all offsets to (0,0).
Import
This command copies the current layer positions in the workspace and uses them as layer offsets.
Refine
This command tells Chasys Draw IES to attempt to recalculate and refine the offset or rotation of the current layer automatically using its image registration algorithm. It uses the current offset or rotation as a reference point for the calculation. Chasys Draw IES will use the selected reference point to do the calculation.
For comparing the images, several functions are provided under “Display”. The default is “DevRoot”, which highlights the differences between the layer being aligned and the reference layer (the first layer).
