Advanced Usage

Generating a Flat

Assuming you're using an editor such as Photoshop that provides multi-layered documents, one way to increase the flexibility of what you can do with the results AstroFlat Pro generates is to use the Flat Only feature to generate just the derived illumination map (commonly referred-to as a "flat") alone into a separate layer in your document. To do this:

• Open your image in Photoshop.
• Duplicate your image layer as a separate layer above the original, naming it e.g., "Flat".
• Run the plug-in, get the flatness looking the way you like, and check the [ ] Flat Only checkbox.
• Complete the plug-in by pressing the [ OK ] button.
• In your editor, set the layer blending mode to Subtract or find other creative ways to use the flat.

After doing this the results from the plug-in will remove the illumination from the original image. The key is that you can now manipulate the "Flat" layer separately by using other operations on just that layer, such as Curves, Levels, smoothing operations, or anything else you find gives you the results you desire. Or you can save the derived flat and use it as input for future runs of your astro stacking software.

Using Selections

AstroFlat Pro doesn't normally need you to select anything in your image to work. However, it's possible to exclude things you know you don't want considered for flattening purposes, such as borders or stacking remnants or even labels, by selecting just the parts you DO want considered using your image editor before starting the plug-in.

If you make a selection before starting the plug-in, you'll see a new Use Selection checkbox appear at the bottom of the dialog that will allow you to choose whether to include or exclude the de-selected pixels (the default is to exclude them). The appearance of this checkbox is an indication that you had made a selection made before starting the plug-in.

Uncheck the Use Selection checkbox in order to have the plug-in include all the pixels in the image for flattening. Toggle it back and forth to see the differences between including and excluding those pixels.

Using the plug-in as a Smart Filter in Photoshop

AstroFlat Pro can also be used as a Photoshop Smart Filter, in which it can be stacked with other filters over your image and run "non-destructively" on your image pixels. To use the plug-in as a Smart Filter:

• Open your image in Photoshop.
• In the menus, choose Filter - Convert for Smart Filters.
• Now run AstroFlat Pro and get the flatness looking as you like.
• Complete the plug-in by pressing the [ OK ] button.
• You will see an entry in the Photoshop Layers panel indicating AstroFlat Pro is now being applied in your Smart Filters stack, and you will see the flattening results on the document.
• At any time you wish to change the parameters to adjust the results, double-click the AstroFlat Pro entry in the Layers panel.

This technique gives you the ability to alter your input image data without having had the flattening applied, and Photoshop will automatically re-apply the flattening (as it does with all filters in a Smart Filter stack). You can also use layer masking to restrict or reduce the opacity of the results.