Color FITS files generally exist in two main types: True Color FITS images and Bayer Pattern FITS images. 


The Split Color FITS files dialog allows you to separate both True Color and Bayer Pattern FITS images into three individual monochrome FITS files, representing the red, green, and blue channels. This allows photometry to be performed on each color channel separately, avoiding inaccuracies introduced by interpolation and ensuring reliable magnitude measurements.



  1. To begin, choose the folder containing your Color FITS images. This is done by pressing the button with 3 horizontal dots next to the Source folder with Color FITS images field. This folder may include a mix of True Color and Bayer Pattern FITS images. Each image will be split into its respective red, green, and blue components.

  2. Next, specify where the separated channel files should be saved, using the Destination folder fields. The red channel FITS files will be stored in the TR folder, the green channel in the TG folder, and the blue channel in the TB folder.

  3. The Bayer channel extractor method applies when working with Bayer Pattern FITS images, and offers 3 methods:

    • Bayer binning: This method directly sums or averages the native Bayer pixels in a 2×2 block, combining the raw red, green, and blue pixel values into one output pixel per channel, without interpolation. The result is a downsampled color image.


Best for:

- Workflows prioritizing raw signal preservation over resolution

- Situations where spatial resolution is less critical (e.g. bright isolated stars)


Photometric Notes:

This method reduces the spatial resolution by a factor of 2 in each image dimension. That trade-off may significantly impact centroid accuracy - especially in crowded fields, as well as the ability to resolve closely spaced target stars or to use small apertures. In undersampled or well-separated targets, Bayer Binning can still offer excellent photometric integrity. But for other purposes, the loss of resolution can reduce accuracy or introduce blending effects.

    • Bayer spreading: This is a lightweight Debayering method designed for speed and minimal computational overhead. It uses a basic interpolation algorithm that averages nearby pixels to reconstruct missing color channels.


Best for:

- Quick looks or previews

- Moderate-quality photometry where extreme precision isn't required


Photometric Notes:

Interpolation near sharp gradients can introduce artifacts or flux redistribution, potentially affecting the accuracy of stellar profiles. While acceptable for basic aperture photometry, it's less suitable for precision work in crowded or undersampled fields.

    • Bilinear demosaicing: This reworked method now uses a sophisticated color interpolation algorithm that takes into account the local structure of the image. It balances color fidelity with spatial detail and is better at preserving the shapes of stars and avoiding color fringes.


Best for:

- General-purpose photometry

- Crowded field photometry or aperture photometry of faint stars


Photometric Notes:

As this method provides improved color channel separation and more accurate reconstruction of the PSF in star images, we recommend it for photometrists who need consistent, clean light curves  

  1. Click the Split button to start. Progress bars will display the status of the conversion.

  2. In case a source file cannot be converted, Phoranso will log the issue and provide details in a log file, that will be reported at the end of the process.

  3. Click Abort if you need to interrupt the conversion at any point.