[R] Weird feature in rimage

From: Alberto Monteiro <albmont_at_centroin.com.br>
Date: Mon, 10 Mar 2008 09:59:31 -0200

I just noticed a weird feature in rimage. It seems that, when reading an image, the line/colums are transposed.

See this reproducible example. The final image should be black - but (as expected) not an absolute black (mean(z) is 0.015, sd(z) is 0.055 but max(z) is 1).

Alberto Monteiro

# reproducible example
# load image of a cat

x <- read.jpeg(system.file("data", "cat.jpg", package="rimage"))
# save the same image of the cat
# weird feature: dimensions are transposed (!)

jpeg("newcat.jpg", width=(dim(x)[2]), height=(dim(x)[1])) par(mar=rep(0, 4))
# load second image of the cat - should be similar but not equal
# (jpeg is a lossy format)

y <- read.jpeg("newcat.jpg")
# Construct the differences

z.mat <- abs(x - y)
z <- imagematrix(z.mat)
# Watch the differences

# Analyse the differences


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