Warning: Peripheral Illumination = Purple corners...

[zmix]

I like to use the "Peripheral Illumination" adjustment set to -3 to get a soft vignette effect, but I've noticed that when shooting in color the corners often have a magenta hue when overexposed, as often happens when shooting against strong backlight.

It also creates some horrible low resolution banding artifacts.. :cry:

Unfortunately, it affects the DNG as well as the JPEG.

I ran some tests to see if this is lens related, but it happens on every lens I have.
I ran a further test by setting the "Peripheral Illumination" adjustment to -3 ("VIC-3")
and shot several frames with no lens attached. Here is an example.

Is there any way to adjust the hue of this effect so that it's a neutral grey rather than magenta?



Note: Both the body and the A12 lens mount have the "latest" firmware: version 1.51, released on June 26, 2012

 

[zmix]

It ruined (or "made" depending on your tastes) a shot I would like to post, but the forum software warned me that:

The image must be at least 0 pixels wide, 0 pixels high and at most 1600 pixels wide and 900 pixels high. The submitted image is 712 pixels wide and 1072 pixels high.


Why is the forum software biased towards horizontal images?


Here is a low resolution screen capture of the image:

 

[streetshooter]

Is there a reason you do this at exposure and not in PP?

I will not try to do this on my GXR but am interested in your reasoning for you workflow. The fact that you see this on the DNG could cause countless hours of no sleep.

 

[zmix]

Hi Don,

1: I like the look of it.

2: It's only a problem in heavily backlit conditions.

3: "PP"? Is this shorthand from "teh internets" for something? (Post Processing, perhaps?)

4: yes, stress...!!!

I've written to Ricoh support about this. Hard to believe that this got past the Beta test stage...

 

[wok64]

The example above raises the question what a DNG really is. Obviously when applying settings like the peripheral Illumination correction the camera no longer provides the data recorded by the sensor but instead data which was exposed to some transformation which applied the correction. It seems this transformation is screwed up and introduces artifacts. A good showcase why one is well advised to get an untweaked DNG out of camera and then do the post processing with software written by experts in image processing instead of relying on the in-camera features.

Of course if Ricoh provides such a feature they should make it work. BTW I assume you´re using the latest firmware and not some early version.

Regarding your color problem there´s also a color correction but I believe in contrast to peripheral Illumination it´s not applied to the DNG file, only to JPEG. For the same reasons I would apply it in post processing anyway.

Wolfgang

 

[zmix]

Hi Wolfgang,

I've edited my original post to indicate the FW version (1.51). It's certainly a problem and I'm happy to share my misfortunes here to help others avoid ruining decent shots.

You are correct that the DNG file should not have any modification or DSP applied, you could say that the GXR's RAW files are COOKED... not a good thing. Especially since the damage done by the internal DSP is impossible to repair in post processing.