Mercurial > hg > octave-image
changeset 474:d3de48ecb728
imrotate: tabs per spaces and keep help text in less characters per line
| author | carandraug |
|---|---|
| date | Mon, 31 Oct 2011 03:03:26 +0000 |
| parents | fcadda4a368c |
| children | 88e70dd531a5 |
| files | inst/imrotate.m |
| diffstat | 1 files changed, 19 insertions(+), 12 deletions(-) [+] |
line wrap: on
line diff
--- a/inst/imrotate.m +++ b/inst/imrotate.m @@ -27,8 +27,15 @@ ## @itemize @w ## @item "nearest" neighbor: fast, but produces aliasing effects (default). ## @item "bilinear" interpolation: does anti-aliasing, but is slightly slower. -## @item "bicubic" interpolation: does anti-aliasing, preserves edges better than bilinear interpolation, but gray levels may slightly overshoot at sharp edges. This is probably the best method for most purposes, but also the slowest. -## @item "Fourier" uses Fourier interpolation, decomposing the rotation matrix into 3 shears. This method often results in different artifacts than homography-based methods. Instead of slightly blurry edges, this method can result in ringing artifacts (little waves near high-contrast edges). However, Fourier interpolation is better at maintaining the image information, so that unrotating will result in an image closer to the original than the other methods. +## @item "bicubic" interpolation: does anti-aliasing, preserves edges better +## than bilinear interpolation, but gray levels may slightly overshoot at sharp +## edges. This is probably the best method for most purposes, but also the slowest. +## @item "Fourier" uses Fourier interpolation, decomposing the rotation +## matrix into 3 shears. This method often results in different artifacts than +## homography-based methods. Instead of slightly blurry edges, this method can +## result in ringing artifacts (little waves near high-contrast edges). However, +## Fourier interpolation is better at maintaining the image information, so that +## unrotating will result in an image closer to the original than the other methods. ## @end itemize ## ## @var{bbox} @@ -101,9 +108,9 @@ ## Compute new size by projecting zero-base image corner pixel ## coordinates through the rotation: corners = [0, 0; - (R * [sizePre(2) - 1; 0 ])'; - (R * [sizePre(2) - 1; sizePre(1) - 1])'; - (R * [0 ; sizePre(1) - 1])' ]; + (R * [sizePre(2) - 1; 0 ])'; + (R * [sizePre(2) - 1; sizePre(1) - 1])'; + (R * [0 ; sizePre(1) - 1])' ]; sizePost(2) = round(max(corners(:,1)) - min(corners(:,1))) + 1; sizePost(1) = round(max(corners(:,2)) - min(corners(:,2))) + 1; ## This size computation yields perfect results for 0-degree (mod @@ -117,7 +124,7 @@ ## homography: oPre = ([ sizePre(2); sizePre(1)] + 1) / 2; oPost = ([sizePost(2); sizePost(1)] + 1) / 2; - T = oPost - R * oPre; # translation part of the homography + T = oPost - R * oPre; # translation part of the homography ## And here is the homography mapping old to new coordinates: H = [[R; 0 0] [T; 1]]; @@ -126,7 +133,7 @@ if (mod(thetaDeg, 90) == 0) nRot90 = mod(thetaDeg, 360) / 90; if (mod(thetaDeg, 180) == 0 || sizePre(1) == sizePre(2) || - strcmpi(bbox, "loose")) + strcmpi(bbox, "loose")) imgPost = rot90(imgPre, nRot90); return; elseif (mod(sizePre(1), 2) == mod(sizePre(2), 2)) @@ -136,9 +143,9 @@ imgPost = zeros(sizePre); hw = min(sizePre) / 2 - 0.5; imgPost (round(oPost(2) - hw) : round(oPost(2) + hw), - round(oPost(1) - hw) : round(oPost(1) + hw) ) = ... - imgRot(round(oPost(1) - hw) : round(oPost(1) + hw), - round(oPost(2) - hw) : round(oPost(2) + hw) ); + round(oPost(1) - hw) : round(oPost(1) + hw) ) = ... + imgRot(round(oPost(1) - hw) : round(oPost(1) + hw), + round(oPost(2) - hw) : round(oPost(2) + hw) ); return; else ## Here, bbox is "crop", the rotation angle is +/- 90 degrees, and @@ -180,7 +187,7 @@ %! ## Verify minimal loss across six rotations that add up to 360 +/- 1 deg.: %! methods = { "nearest", "bilinear", "bicubic", "Fourier" }; %! angles = [ 59 60 61 ]; -%! tolerances = [ 7.4 8.5 8.6 # nearest +%! tolerances = [ 7.4 8.5 8.6 # nearest %! 3.5 3.1 3.5 # bilinear %! 2.7 2.0 2.7 # bicubic %! 2.7 1.6 2.8 ]/8; # Fourier @@ -192,7 +199,7 @@ %! - 10*(X/5 - X.^3 - Y.^5).*exp(-X.^2-Y.^2) \ %! - 1/3*exp(-(X+1).^2 - Y.^2); %! -%! x -= min(x(:)); # Fourier does not handle neg. values well +%! x -= min(x(:)); # Fourier does not handle neg. values well %! x = x./max(x(:)); %! for m = 1:(length(methods)) %! y = x;