Using Clipping on an image

I see a problem with the overflow, but in theory, you can easily sum said number to the image, this is the matlab algorithm transformed to julia

using Images, TestImages
img = TestImage("mandrill")
im = Gray.(img)
im = float64(img2) #im = double(im)
(ren, col) = size(im)
img2 = zeros(ren,col)
k = 100/255
for i = 1:re
for j = 1:col
im [i, j] = im[i, j]+k
end
end

Respecting the clipping, i really don´t know, i’m not a professional, even an amateur, in that area.