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Histogram in BackyardEOS


gperuzzo
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Hello averyone.

I´m making a homemade flatbox and testing the funtionality I verify histogram of adquisition. I found that the position of RGB in the Histogram in BYE is diferent that the one of Pixinsight using the same RAW image.

Below a picture of the BYE screen

image.png.70b49aaee22310e1c6b80c64e6442116.png

And below the same image but with the histogram in Pixinsight

image.png.23bbc3a0a217492a645f4eba53216e8f.png

 

As you can see R G B in backyardEOS and G B R in Pixinsight

Have anybody idea what are I making bad or how is the way BYE show the histogram?

 

thanks in advance and kind regards.

 

Gabriel

 

 

 

 

 

 

 

 

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Yes,

This has been discussed a few times, but not recently.

The histogram that BYE displays is created from the JPG image that is embedded in the RAW image. I would suggest that it is not suitable for determining your flat frame exposures, because the embedded JPG has been auto-stretched and color balanced in the camera.

I would suggest getting a starting point for the exposure of your flats by putting the camera in AV mode and selecting AV as the shutter in BYE. When you take an image, the cameras exposure circuitry will determine an exposure. You can then switch the camera back to Manual adjust the exposure as necessary to get a flat frame that you are happy with. Just be sure that PI does not base the histo on a stretched image.

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As discussed long ago:

The Histogram values for use with Flat Frames is nowhere near as critical as in the ages of Film and earlier generations CCD Imagers.  As long as the Histogram is well away from EITHER edge of the Histogram, the Flat-handling Software (whether PixInsight or DSS or APP or other) will handle the Flat Images.  Those Images are, after all, Averaged and Scaled to the Range of 0-1.  The status of each component Color in an RAW Image is also of NO Importance, as the Flats process uses the Original Bayered Data which precedes the Image being Debayered and Colors Assigned.

(The historical reason for specific ADU values:  Film and early CCD Sensors had rather Non-Linear Response Curves - AP Imaging "Hyper-ed" Film depended on that Non-Linearity - and Under- / Over-Exposure was exacerbated by such Non-Linearity.  This is No Longer an Issue for Modern CCD or CMOS Sensors such as those found in ANY Consumer Camera.)

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