Histogram Equalization

General Usage
25

Okay to reduce the confusion I went ahead an installed TestImages. Here’s what’s happening (I think):

julia> using Images, TestImages

julia> image = testimage("cameraman.tif");

julia> typeof(image)
Array{Gray{Normed{UInt8,8}},2}

So image is an array of Gray{Normed{UInt8,8}} elements:

julia> image[1,1]
Gray{N0f8}(0.612)

If you multiply those by an Int, as you do, you end up with:

julia> image[1,1]*255
Gray{Float32}(156.0f0)

that doesn’t work for indexing, you need an integer. You converted this back to UInt8:

julia> UInt8(image[1,1]*255)
0x9c

but then you’re directly adding a 1, which as we said is just a literal that gets parsed as an Int64, and adding that to your UInt8 just gives you a regular Int:

julia> UInt8(image[1,1]*255)+1
157

So this is essentially the same as doing:

julia> Int(image[1,1]*255)+1
157