Re: Materials for Flat-Fielding
Re: Materials for Flat-Fielding
- Subject: Re: Materials for Flat-Fielding
- From: Ray Maxwell <email@hidden>
- Date: Fri, 01 Jun 2007 19:01:27 -0700
Hi Ken,
It is almost impossible to get a flat diffuse reflector with a perfect
surface and to light it evenly. In order to do a gain calibration on
early CCD radiometric sensors that I designed for the Canadian Center
for Remote Sensing we used an integrating sphere. It has a light source
inside that bounces all around in the sphere and gives you a very even
input to your camera or sensor. The camera is set to focus at
infinity. This is a method of creating an even input to camera or
radiometric sensor for precision calibration.
Hope this explains what the others are suggesting.
Ray Maxwell
Ken Fleisher wrote:
Since I got two responses for spheres, I'm not sure if I explained my
question correctly. I am using the Sinar CaptureShop software to do
what they term a "Scene Reference", which is also known as
flat-fielding. It corrects for light fall-off and spatial
non-uniformity of the light due to other reasons. I capture an image
of a white card to determine the nature of the light
fall-off/irregularity. In order to work well, it is critical that the
card is very uniform on the surface.
My question is pertaining to materials for the white card to take the
image of since I am not completely satisfied with the ones that we are
currently using. I don't understand what a sphere would have to do
with this, but if I'm missing something, please explain.
Thanks!
On Jun 1, 2007, at 5:27 PM, Roger Breton wrote:
A sphere is always the best idea but they ain't cheap. Some come up for
sales on eBay once in a blue moon but that's it.
Translucent white plexiglass?
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden