Question

I need to write some ruby script which will help me with big image files. I know basics of imagemagick and rmagick library(ruby), but till now I was doing generally simple things (thumbnailing, adding watermarks etc.) Now I want to cut file with example resoultion 3000/1000px into ten smaller images (3000/100 px). Is it possible? I have no idea which method to use.

Answer 1

How about cropping the input image once for each of the output images:

output_images =
  (0...10).collect { |i|
    input_image.crop(0, i*100, 3000, 100, true)
  }

More generally (but still assuming the Y resolution is divisible by the number of slices):

def slice_image_horizontally(image, num_slices)
  slice_height = image.y_resolution / num_slices
  (0...num_slices).collect { |i|
    image.crop(
      0, i * slice_height,
      image.x_resolution, slice_height,
      true # reset image offset
    )
  }
end

http://www.imagemagick.org/RMagick/doc/image1.html#crop