Mercurial > ift6266
diff writeup/nips2010_submission.tex @ 517:0a5945249f2b
section 2, quick first pass
author | Dumitru Erhan <dumitru.erhan@gmail.com> |
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date | Tue, 01 Jun 2010 11:14:48 -0700 |
parents | d057941417ed |
children | 460a4e78c9a4 |
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--- a/writeup/nips2010_submission.tex Tue Jun 01 11:04:09 2010 -0700 +++ b/writeup/nips2010_submission.tex Tue Jun 01 11:14:48 2010 -0700 @@ -157,7 +157,7 @@ proportionally to its height: $shift = round(slant \times height)$. The $slant$ coefficient can be negative or positive with equal probability and its value is randomly sampled according to the complexity level: -e $slant \sim U[0,complexity]$, so the +$slant \sim U[0,complexity]$, so the maximum displacement for the lowest or highest pixel line is of $round(complexity \times 32)$.\\ {\bf Thickness.} @@ -187,9 +187,9 @@ \times complexity]$ and $c$ and $f$ $\sim U[-4 \times complexity, 4 \times complexity]$.\\ {\bf Local Elastic Deformations.} -This filter induces a "wiggly" effect in the image, following~\citet{SimardSP03-short}, +This filter induces a ``wiggly'' effect in the image, following~\citet{SimardSP03-short}, which provides more details. -Two "displacements" fields are generated and applied, for horizontal +Two ``displacements'' fields are generated and applied, for horizontal and vertical displacements of pixels. To generate a pixel in either field, first a value between -1 and 1 is chosen from a uniform distribution. Then all the pixels, in both fields, are @@ -200,13 +200,13 @@ $\alpha = \sqrt[3]{complexity} \times 10.0$ and $\sigma = 10 - 7 \times \sqrt[3]{complexity}$.\\ {\bf Pinch.} -This GIMP filter is named "Whirl and -pinch", but whirl was set to 0. A pinch is ``similar to projecting the image onto an elastic +This is a GIMP filter called ``Whirl and +pinch'', but whirl was set to 0. A pinch is ``similar to projecting the image onto an elastic surface and pressing or pulling on the center of the surface''~\citep{GIMP-manual}. -For a square input image, think of drawing a circle of +For a square input image, this is akin to drawing a circle of radius $r$ around a center point $C$. Any point (pixel) $P$ belonging to that disk (region inside circle) will have its value recalculated by taking -the value of another "source" pixel in the original image. The position of +the value of another ``source'' pixel in the original image. The position of that source pixel is found on the line that goes through $C$ and $P$, but at some other distance $d_2$. Define $d_1$ to be the distance between $P$ and $C$. $d_2$ is given by $d_2 = sin(\frac{\pi{}d_1}{2r})^{-pinch} \times @@ -222,31 +222,32 @@ \vspace*{1mm} {\bf Motion Blur.} -This GIMP filter is a ``linear motion blur'' in GIMP +This is a ``linear motion blur'' in GIMP terminology, with two parameters, $length$ and $angle$. The value of -a pixel in the final image is the approximately mean value of the $length$ first pixels +a pixel in the final image is approximately the mean value of the $length$ first pixels found by moving in the $angle$ direction. Here $angle \sim U[0,360]$ degrees, and $length \sim {\rm Normal}(0,(3 \times complexity)^2)$.\\ {\bf Occlusion.} -This filter selects a random rectangle from an {\em occluder} character +Selects a random rectangle from an {\em occluder} character images and places it over the original {\em occluded} character image. Pixels are combined by taking the max(occluder,occluded), -closer to black. The corners of the occluder The rectangle corners +closer to black. The rectangle corners are sampled so that larger complexity gives larger rectangles. The destination position in the occluded image are also sampled according to a normal distribution (see more details in~\citet{ift6266-tr-anonymous}). -It has has a probability of not being applied at all of 60\%.\\ +This filter has a probability of 60\% of not being applied.\\ {\bf Pixel Permutation.} This filter permutes neighbouring pixels. It selects first $\frac{complexity}{3}$ pixels randomly in the image. Each of them are then -sequentially exchanged to one other pixel in its $V4$ neighbourhood. Number -of exchanges to the left, right, top, bottom are equal or does not differ +sequentially exchanged with one other pixel in its $V4$ neighbourhood. The number +of exchanges to the left, right, top, bottom is equal or does not differ from more than 1 if the number of selected pixels is not a multiple of 4. -It has has a probability of not being applied at all of 80\%.\\ +% TODO: The previous sentence is hard to parse +This filter has a probability of 80\% of not being applied.\\ {\bf Gaussian Noise.} This filter simply adds, to each pixel of the image independently, a noise $\sim Normal(0(\frac{complexity}{10})^2)$. -It has has a probability of not being applied at all of 70\%.\\ +It has a probability of 70\% of not being applied.\\ {\bf Background Images.} Following~\citet{Larochelle-jmlr-2009}, this transformation adds a random background behind the letter. The background is chosen by first selecting, @@ -280,7 +281,7 @@ This filter has a probability of not being applied at all of 75\%.\\ {\bf Scratches.} The scratches module places line-like white patches on the image. The -lines are heavily transformed images of the digit "1" (one), chosen +lines are heavily transformed images of the digit ``1'' (one), chosen at random among five thousands such 1 images. The 1 image is randomly cropped and rotated by an angle $\sim Normal(0,(100 \times complexity)^2$, using bi-cubic interpolation,