Build 2023Feb10
All files recorded with stock build.
Only change to the presets is 2.39:1 ratio and 14/12bits when required.
First, you can have a look at the files contained here (Small Download):
http://bit.ly/3E2bhdcYou will see the real power of Dual ISO. This is as challenging as it gets for a scene. Lots of dark and very bright areas. There are 3 files, one at ISO 100, the same ISO 100 brightened and the same scene recorded at Dual ISO 100/3200 with same brightness settings applied (exposure -1.71 and Lighten 93) .
No noise reduction was used. As you will see, the gain in shadows quality is phenomenal.
I salute the amount of work and tweaking put into that build to reach such a result.
Now, as I briefly outlined in a previous post, the way the image is exposed is of paramount importance.
For example here is a reference image recorded at ISO 100, -1.0 EV
Here is the same scene recorded at Dual Iso 100/800, exposed -1.0 EV for ISO 100:
By looking at the waveform monitor, you can see that although there is still headroom left, the flat line indicates that some Limiting / Clipping is taking place in camera.
Same Scene with Dual ISO Processing Applied:
In this example, iimage looks fine. But the amount of clipping will dictate how the file will look when played. Sometimes it will be fine, sometimes you will get pink highlights and sometimes the quality of the file will be seriously diminished and flickering will be introduced.
I included several example MLV files at the end of the post, so you can all judge for yourselves.
Same Scene recorded at Dual ISO 100/800, but exposed at -1.0 EV for ISO 800 before Dual ISO Processing:
As you can see on the waveform, there is far less Limiting / Clipping happening, as you don't see a total flatline in the red at the top, from left to right.
Same scene as above, with Dual ISO processing applied:
As you can see, the scene is a lot darker. When exposing this way, there won't be any visible Dual ISO artifacts nor flicker under normal circumstances. But once you brighten up the scene, you will gain some level of noise in the midtones.
So in order to find the proper exposure point, we would need to know what happens in camera regarding the exposure of both ISO's and how limiting is applied. Otherwise the results will be too unpredictable, depending on the overall brightness of the scene, the presence of reflective objects, etc. If we underexpose to the max just to play safe, we lose some of the benefits gained by using Dual ISO in the first place.
It is also unclear where MlvApp sets the pivot points between Swadows, Midtones and Highlights. Ideally, the Midtones should not be touched by the Dual ISO processing.
A happy balance has to be reached.
For the MLV files I included, pay attention to those areas of interest when evaluating:
Those are the areas where artifacts are most likely to occur.
I recorded the files on 2 different days. One day was sunny and the other had an overcast sky. The effects of brightness on the image will be obvious.
I included 2520x1054 23.976p files, and also 1736x2178 20p files, as the latter emphasize the effects of brightness, binning and scan rate on the image.
p.s. There is some vignetting in some of the examples, because I forgot to bring a large ND filter to put on the wide lens.
Link To the MLV Files (Large 3GB Download):
http://bit.ly/3RT9RXW (will erase in 1 week)
Finally, when testing, one has to do at least 4-5 recordings per setting. The timestamps on the files will show that two recordings in a row may give two different results. So some problems may be hard to pinpoint, reproduce or observe when only recording once or twice.
