No function uses PS_INTERPOLATE_*_VARIANCE?

[robert.desonia@…]

The description for psImageInterpolateMode (section 4.6.3 in PSDC-430-007-12)
states that the *_VARIANCE enum values would require modification of a variance
image, but no function that uses psImageInterpolateMode has a variance image
input, as far as I can see.

Can you give me some additional information on implementation of the *_VARIANCE
interpolate modes?

-rdd

[Paul Price]

The VARIANCE options aren't to support current psLib or psModule functions, but
rather to support the image combination step. I use them in my prototype image
combination program.

The idea is this: we have an input image, which we need to shift (using
psImagePixelInterpolate). The input image has an associated variance image,
which tells us the errors in the flux values for each pixel (using Poisson
statistics --- square root of the number of counts, plus some other stuff).
We'd like an error map for the shifted image.

I have a modified version of the PS_INTERPOLATE_BILINEAR option available as a
guide.

[Paul Price]

Demonstration of PS_INTERPOLATE_BILINEAR_VARIANCE

[robert.desonia@…]

So, the interpolation will not interpolate on the image and variance image
simultaneously; that is where I went astray.

So, I assume that the variance versions of the pixel interpolate will be folded
into psLib, i.e., there will be lower level functions like
p_psImagePixelInterpolateBILINEAR_VARIANCE available and all the functions
taking a psImageInterpolateMode parameter will be cognizant of the variance
interpolation modes.

[Paul Price]

The VARIANCE options need to be available in psImagePixelIterpolate (I love that
function!) in order to allow doing general warping of images. I understand that
other functions that warp images (e.g., psImageRotate) use
psImagePixelInterpolate, so I don't expect it would be difficult to make them
use the VARIANCE options either; but this is not necessary immediately.

[robert.desonia@…]

I think that this is clearly understood now.