Hi,
Just noticed this today as I was editing some snapshots of Mars. Because it's such a pin-point, this effect really stands out.
Open Levels and Color to default settings, and Mars becomes quite hazy and blurry, without any alterations in the transformation.
I don't notice this effect on other images, but I will start to look for images with small dots of light.
Any ideas on what might be going on?
odd effect in Levels and Color
Moderator: jsachs
Re: odd effect in Levels and Color
I updated to 8.0.164, but no improvement.
In fact, things look even weirder in HSL:
In fact, things look even weirder in HSL:
Re: odd effect in Levels and Color
Do you have show highlight and shadow clipping turn on?
Jonathan Sachs
Digital Light & Color
Digital Light & Color
Re: odd effect in Levels and Color
No, they're not on. I tried with them on and off and there's no difference.
I use Levels and Color almost all the time, and this is the first time I've seen this effect.
To be clear, this is what I see when I first open L & C, with no adjustments at all.
I use Levels and Color almost all the time, and this is the first time I've seen this effect.
To be clear, this is what I see when I first open L & C, with no adjustments at all.
Re: odd effect in Levels and Color
Any saved default settings file? If so, rename it so it will not be loaded and try again. If that fixes it, please send me the settings file.
Jonathan Sachs
Digital Light & Color
Digital Light & Color
Re: odd effect in Levels and Color
The only settings file in the Levels and Color folder is: Previous.levels and color
I renamed it, and tried again, but no change - same effect.
This is what the file settings are:
levels_and_color 0 colorspace 1 dynamic_range 1 auto_wb 0 v1 1 v2 168 brightness 0 contrast 0 saturation 0 colorbal_remove ffffff colorbal_add ffffff probesize 2 display 2 sync_scroll 1 auto_preview 1 amount 1 -1 0 1 ″Amount: ″ ″Mask″
I renamed it, and tried again, but no change - same effect.
This is what the file settings are:
levels_and_color 0 colorspace 1 dynamic_range 1 auto_wb 0 v1 1 v2 168 brightness 0 contrast 0 saturation 0 colorbal_remove ffffff colorbal_add ffffff probesize 2 display 2 sync_scroll 1 auto_preview 1 amount 1 -1 0 1 ″Amount: ″ ″Mask″
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Re: odd effect in Levels and Color
Does it also happen if Color Balance is reset from Custom? And only in HSL, not in HSV?
Maciej Tomczak
Phototramp.com
Phototramp.com
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Re: odd effect in Levels and Color
I think I know what may be the reason - the small number of 'white' Mars pixels and the internal threshold default for the number of pixels that Levels and Colour ignores to set the white point (or none of the Mars pixels has all 3 channels maxed out). It looks like the latter.
The dynamic range highlight tick decided to become 72.9% instead of being 100% or close, and the highlight slider matched this position when Dynamic Range was set to Reset. As a result, the highlight slider reduced the HSL-L values of the Mars pixels way down the upper HSL cone causing the maxed out pixels in some, but not all channels to get saturated.
If the white point slider is moved to the right, or set to Full, those pixels should become 'white' again.
The dynamic range highlight tick decided to become 72.9% instead of being 100% or close, and the highlight slider matched this position when Dynamic Range was set to Reset. As a result, the highlight slider reduced the HSL-L values of the Mars pixels way down the upper HSL cone causing the maxed out pixels in some, but not all channels to get saturated.
If the white point slider is moved to the right, or set to Full, those pixels should become 'white' again.
Maciej Tomczak
Phototramp.com
Phototramp.com
Re: odd effect in Levels and Color
I think you may have put your finger on it.
The threshold for finding the black and white points in Levels and Color is pre-set at 0.01%, so if the area of the image covered by the white objects is less than that percentage of the total number of pixels they will be ignored and an incorrect white point will be selected. There is also something similar in the auto white balance setting.
Levels and Color is a simplified version of the Adjust transformation, and it is definitely not optimized for processing astro images. Adjust should work much better since it uses a curve instead of sliders.
If you want me to look into it further, I will need a copy of the image you are using.
The threshold for finding the black and white points in Levels and Color is pre-set at 0.01%, so if the area of the image covered by the white objects is less than that percentage of the total number of pixels they will be ignored and an incorrect white point will be selected. There is also something similar in the auto white balance setting.
Levels and Color is a simplified version of the Adjust transformation, and it is definitely not optimized for processing astro images. Adjust should work much better since it uses a curve instead of sliders.
If you want me to look into it further, I will need a copy of the image you are using.
Jonathan Sachs
Digital Light & Color
Digital Light & Color
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Re: odd effect in Levels and Color
Mark's image is some 16 million pixels. 0.01% of that would be 1600 brightest pixels that, if I understand it well enough, are then averaged to find the value of the white point. By my estimate, there are not more than 500 almost white Mars pixels, so less bright pixels (and probably some almost black) are included in calculating the average and end up with the white point of the image being computed as 72.9%, I think.
You could experiment with Auto Range, where the thresholds are user-adjustable, and see whether reducing the white point threshold would drastically increase the white point value of your image.
You could experiment with Auto Range, where the thresholds are user-adjustable, and see whether reducing the white point threshold would drastically increase the white point value of your image.
Maciej Tomczak
Phototramp.com
Phototramp.com