Color noise

Empty sky at full size, stretched. Pixels of different colors are scattered where the background should be an even gray.

1. 01

   Not enough integration

   Too few hours on the target leaves noise that stretching makes visible, and on a color camera it shows as color.

   FixAdd integration time. The Sub-Exposure & Calibration Planner gives the hours a clean stack needs under your sky.

   Sub-Exposure & Calibration Planner
2. 02

   No chroma noise reduction

   Color noise that remains after stacking needs its own reduction step.

   FixApply a chroma noise reduction step, lightly.

3. 03

   Gain too low for the sky

   At low gain many CMOS cameras have more read noise, so each sub needs longer before the sky buries it. Subs too short for the gain leave read noise in the stack.

   FixFind the sub length that swamps read noise at your gain and sky, then lengthen the subs or raise the gain to meet it.

   Sub-Exposure & Calibration Planner

The atlas lists no look-alike for this one.

The finished image shows the speckle. Whether the total hours or the sub length fell short needs your sub length, gain and total integration.

An even gray background at full size, at the stretch you want.

No outside source is cited here. The signature, the causes and their order are the atlas’s own, from imaging experience. The order is a judgment of likelihood; no measured frequency is behind it.