Craig Stocks
Well-known member
I've spent a fair amount of time this morning experimenting with frame averaging on the IQ4150. I posted yesterday that frame averaged results are far superior to single frames in terms of noise but I also wanted to compare to traditionally stacked and averaged images using Photoshop.
Observations and questions:
Frame averaging can greatly reduce noise which allows a lot of latitude to lift exposure and shadows without incurring excessive noise.
It does not (my opinion) increase dynamic range. Bright highlights and deep shadows are equally recoverable in a single frame or FA, there's just less noise when averaged. Exposing for the highlights and lifting shadows in post can yield a clean image, but it doesn't automatically do any tone mapping.
Taking individual frames and averaging in Photoshop is no worse and may be slightly better than averaging in the IQ4150. Note that in this test I pushed exposure, etc. in Capture One working with RAW files and then stacked the resulting images.
I have seen some magenta artifacts when bright highlights are present for only a small portion of the total frame average exposures. I'm still exploring this issue and working with my dealer.
The explanation from Phase One is still somewhat convoluted. I'm curious if it does the calculations on RAW date or after demosaicing. Stacking in Photoshop has to be done on a demosaiced image.
Samples and test:
I arranged a simple, high contrast scene in my studio. All samples were captured at ISO 50 @ 1 second and I used 10-frame stacks for comparison. I processed all frames in Capture One by setting the WB to Tungsten, and then pushed Exposure, Highlights and Shadows to the max. I also pushed contrast almost to the max.
I exported the test images as 16-bit ProPhoto PSDs and stacked in Mean stacking mode in Photoshop for comparison.
The samples here were cropped to 100% and saved as sRGB JPEGs.
Observations and questions:
Frame averaging can greatly reduce noise which allows a lot of latitude to lift exposure and shadows without incurring excessive noise.
It does not (my opinion) increase dynamic range. Bright highlights and deep shadows are equally recoverable in a single frame or FA, there's just less noise when averaged. Exposing for the highlights and lifting shadows in post can yield a clean image, but it doesn't automatically do any tone mapping.
Taking individual frames and averaging in Photoshop is no worse and may be slightly better than averaging in the IQ4150. Note that in this test I pushed exposure, etc. in Capture One working with RAW files and then stacked the resulting images.
I have seen some magenta artifacts when bright highlights are present for only a small portion of the total frame average exposures. I'm still exploring this issue and working with my dealer.
The explanation from Phase One is still somewhat convoluted. I'm curious if it does the calculations on RAW date or after demosaicing. Stacking in Photoshop has to be done on a demosaiced image.
Samples and test:
I arranged a simple, high contrast scene in my studio. All samples were captured at ISO 50 @ 1 second and I used 10-frame stacks for comparison. I processed all frames in Capture One by setting the WB to Tungsten, and then pushed Exposure, Highlights and Shadows to the max. I also pushed contrast almost to the max.
I exported the test images as 16-bit ProPhoto PSDs and stacked in Mean stacking mode in Photoshop for comparison.
The samples here were cropped to 100% and saved as sRGB JPEGs.
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