ABSTRACT
The Pleiades open cluster M45 is a challenging subject at the best of times on account of its enormous dynamic range between the bright stars in the cluster and the faint reflection nebulosity. Those issues were compounded by sub-optimal calibration files. The sparse RGB files were barely passable. All files had suspicious random dark pixels that suggested further calibration issues. The luminance channel showed promise, with good background detail of the faint nebulosity. The luminance channel follows a modified standard processing sequence to reduce star bloat. The color processing follows the familiar path of combination, background neutralization and stretching, with a few minor alterations: Prior to stretching, the dark pixels were filled in and color calibration was omitted. Green pixels were then removed with the Selective Color Noise Reduction tool and the A Trous Wavelet Transform tool used to blur the image at a small scale before applying a medium stretch with the Histogram Transformation tool.
