Any thoughts on the difference between changing the ASA setting versus changing the EV setting?
Obviously, they accomplish the same thing in a different fashion. Setting the EV one stop low gives the same exposure as setting the ASA one stop higher. The question is, what is the difference in terms of noise? Is it necessary to make a family of noise profiles for each EV and ASA, or would it be accurate to just do some type of total exposure compensation (how many stops off from an "ideal" exposure)
Visually, lowering the EV looks a lot like increasing the ASA, but I haven't done any scientific testing.
ASA versus EV affect on noise?
Regarding the EV setting, the setting of what is it? - Of a camera or of some software?
In camera, exposure compensation changes the exposure time. The exposure time does not significantly influence the noise properties.
Normally building a set of profiles for every ISO setting is suffucient, especially if profiles are auto-fine-tuned when applied.
In camera, exposure compensation changes the exposure time. The exposure time does not significantly influence the noise properties.
Normally building a set of profiles for every ISO setting is suffucient, especially if profiles are auto-fine-tuned when applied.
camera exposure compensation setting
Most digicams have an exposure compensation setting that seems to adjust the automatic metering system to over or under exposure the scene. So, if a perfectly metered scene is 1/100 second adjusting the EV for -1.0 (stops) will adjust the exposure and use 1/200 seconds, will the result being darker than normal.
To me, this a lot like "push-processing" in the old days of film, where we push TriX from 400 to 800 ASA with an increase in noise.
Consider an indoor basketball game. I need a fast shutter speed and my camera is only rated for up to ASA 400. I underexposure by one step to get an effective ASA of 800, then adjust the final image in my computer for proper brightness. This works and is better than blurred action, but increases the noise levels, so I use NI to bring the noise back down. The results can be very good.
To me, this a lot like "push-processing" in the old days of film, where we push TriX from 400 to 800 ASA with an increase in noise.
Consider an indoor basketball game. I need a fast shutter speed and my camera is only rated for up to ASA 400. I underexposure by one step to get an effective ASA of 800, then adjust the final image in my computer for proper brightness. This works and is better than blurred action, but increases the noise levels, so I use NI to bring the noise back down. The results can be very good.
does batch processing use Exposure bias?
Exposure bias : 0.0 eV is available in the EXIF setting, and Neat Image will copy the EV information to the file.
Does Neat Image use this information/setting in automatic batch processing to determine the best profile? That is, if I profile for EV = 0 and EV = -1 will NI pick the best profile.
thansk for all your answers. I've been a NI user for about a year now but am trying to improve my skills now, hence all the questions.
Does Neat Image use this information/setting in automatic batch processing to determine the best profile? That is, if I profile for EV = 0 and EV = -1 will NI pick the best profile.
thansk for all your answers. I've been a NI user for about a year now but am trying to improve my skills now, hence all the questions.
You have spelled the key point here - the camera only changes the exposure time, which leaves the noise levels the same (as with no exposure compensation) but then you adjust the image in the editor, which increases the noise level. So, if you apply Neat Image to the image directly from camera (before doing any Photoshop adjustments) then the noise is still low and exposure compensation does not matter. After you amplify noise (along with all image elements) in Photoshop, you basically get another image with Photoshop-adjusted noise levels. This adjustment may or may not be proportional to the camera EV value.
In-camera exposure compensation is not used to match profiles. It is not listed in the user guide as one important parameter in the list of parameters that significanly affect the noise.
Vlad
In-camera exposure compensation is not used to match profiles. It is not listed in the user guide as one important parameter in the list of parameters that significanly affect the noise.
Vlad