Show rotation around center and around head

blog/_posts/2017-04-18-offset-arrays.md

@@ -149,10 +149,13 @@ give them all the same indices, and `colorview(RGB, r, g, b)` inserts
 the grayscale images `r`, `g`, and `b` into the red, green, and blue
 channels respectively.  If we visualize `cv`, we see the following:
 
-![cameraman_overlay](/blog/_posts/offsetarrays_figures/cameraman_overlay.png)
+| around image center | around head (cv) |
+|:-------------------:|:----------------:|
+| ![cameraman](/blog/_posts/offsetarrays_figures/cameraman_overlay_center.png) | ![cameraman_rot](/blog/_posts/offsetarrays_figures/cameraman_overlay.png) |
 
-which indeed confirms that the rotation is around the head. Alternatively,
-we can focus on the overlapping portions of these images like this:
+The right image (corresponding to the steps taken above) indeed
+confirms that the rotation is around the head. Alternatively, we can
+focus on the overlapping portions of these images like this:
 
 ```julia
 julia> inds = map(intersect, indices(img), indices(img_rotated))

blog/_posts/offsetarrays_figures/figures.jl

@@ -10,6 +10,11 @@ save("cameraman.png", img)
 save("cameraman_rotated.png", clamp01nan.(img_rotated))
 cv = colorview(RGB, paddedviews(0, img, img_rotated, img)...)
 save("cameraman_overlay.png", clamp01nan.(cv))
+pimg = parent(img)
+tfmcntr = recenter(RotMatrix(-pi/6), center(pimg))
+img_rotated_cntr = warp(pimg, tfmcntr)
+cvc = colorview(RGB, paddedviews(0, pimg, img_rotated_cntr, pimg)...)
+save("cameraman_overlay_center.png", clamp01nan.(cvc))
 inds = map(intersect, indices(img), indices(img_rotated))
 cvi = colorview(RGB, img[inds...], img_rotated[inds...], img[inds...])
 save("cameraman_overlay_interior.png", clamp01nan.(cvi))