astrometric scaling of `fgain`

[hgao-astro]

swarp/src/field.c

Lines 1068 to 1077 in bf4f496

	if (inscale!=0.0 && outscale!=0.0)
	{
	if (scaleflag)
	{
	field->fascale = (outscale/inscale);
	field->fsaturation = field->saturation*field->fascale;
	}
	else
	field->fgain = field->gain*(inscale/outscale);
	}

Dear SWarp authors,

I don't understand why the effective gain is scaled by inscale/outscale instead of outscale/inscale when pixel values are not scaled. When resampling images to larger pixels, the variance should become smaller and therefore the effective gain should be larger, given that pixel values are not scaled up. Let me know if there was a misunderstanding of the codes.

Thanks,
Hua