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can some one please explain to me why the tiff is wors than the jpeg after stacking in dss i set the eos 1100d to save both raw and jpeg. the raw files are 4x6 minit and 1x8 minit exposures and there are the same in darks with 6 flats and 6 dark flats .

its just that every time i stack with raw files they are poo but the jpeg with no flats or darks seem much better.

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my astro pics

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JPEG from the camera is strongly gamma-stretched from the raw image, so that the various color levels fit within the 8-bit range of JPEG, which means this kind of rendering is not linear to the signal actually recorded.

Conversely, DSS works with the actual signal from your RAWs and produces an unstreched image in the TIFF. Additionally the TIFF has more "depth" being at least 16-bit if not 24 or 32. So when viewed directly the TIFF is a lot less bright, but should actually contain far more precise data from stacking.

You must use a full-depth aware image editing application (Photoshop, Lightroom, Startools, Pixinsight, Fotoxx, Gimp 2.9+ come to mind, and many others I don't know of) to "stretch" the levels with software tools:

- either a brightness tool, one that does'nt change the color balance

- or a "levels" tool, to set the black/white/mid points (typically within an histogram), which is a gamma strech -- avoid if you can use a brightness stretch instead, since it will change colors

You may also have to repeat the streching a few times to bring the faint signal into "acceptable" levels.

And you have a very nice image, with very fine details.

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