New feature – logarithmic horizontal axis option in live stack histogram

Discussions of Electronically Assisted Astronomy using the Live Stacking feature.
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New feature – logarithmic horizontal axis option in live stack histogram

Post by admin » Thu Jan 10, 2019 10:12 pm

Hi,

just uploaded a new build of SharpCap 3.2 and this has a little new feature in it giving the option to switch the live stack histogram view between a linear horizontal axis and a logarithmic horizontal axis. Why might you want to do that? Well with the logarithmic horizontal axis, the black and mid levels (which are the ones you usually want to adjust when setting up the display stretch to pull out the faint detail) have much more space horizontally in the graph so you're not trying to move them one pixel at a time as carefully as you can with the mouse – instead you have plenty of space in the centre of the graph to adjust them nicely.

Here's a picture of what the histogram looks like with the new logarithmic scaling in place
Capture.JPG
Capture.JPG (43.41 KiB) Viewed 379 times
and here's what the histogram looks like with the logarithmic scaling turned off
Capture2.JPG
Capture2.JPG (44.7 KiB) Viewed 379 times
As you can see, with the logarithmic scaling on the much more horizontal space is given to the darker areas of the histogram which are precisely the areas we are concentrating on typically in Astro imaging.

Hope this is useful.

Cheers, Robin

pjwack
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Re: New feature – logarithmic horizontal axis option in live stack histogram

Post by pjwack » Sat Jan 12, 2019 8:41 pm

Very useful! On a somewhat related note, moving the "auto-intensity" slider from settings to a slider in the histogram might be more user friendly.

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Re: New feature – logarithmic horizontal axis option in live stack histogram

Post by admin » Sat Jan 12, 2019 8:51 pm

Ah, funny you should mention that…

I also added a way to use a stronger or weaker auto stretch by holding down the control key (stronger) or the shift key (weaker) when you press the auto stretch button. This applies both in the life stacking histogram auto stretch and in the many histogram auto stretch. I would prefer not to put any more controls into the UI of the life stacking as it's quite complicated enough already (and probably getting it a bit intimidating to new users) so hopefully this sort of improvement offers more control to power users without making things more confusing to newbies.

Cheers, Robin

Steve Teel
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Re: New feature – logarithmic horizontal axis option in live stack histogram

Post by Steve Teel » Sat Jan 12, 2019 9:01 pm

Thanks Robin. Already this partially answers the question of how to save a LINEAR image "as viewed": one can move the midtones slider to the midpoint between the shadows setting and highlights setting to approximate a linear stretch--as long as the horizontal scale is linear. The "Reset" button moves the sliders to EXACT default points, but the installation default is not linear. Is there a way to set the default to (0%, 50%, 100%) to achieve precise linearity?

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