First Assignment

Objective: Process raster images using simple pixelwise operations and add interactivity.
Setup a page with at least two canvases. Draw the original input image in the first one, process its data using pixelwise operations, and put the content of the output images in the other canvases.

Question #1: Decomposition into individual components:

Keep only the R component, setting the G and B components to zero.

Basic Image Processing

Image 1

Image 2


Question 2: Thresholding of grey-scale image

Convert the image to grey-level by averaging the R, G, B components. Threshold the grey-level image at grey level threshold=120.

Image 1

Image 2

Question 3: Linear correction

Apply a linear correction on the pixel values R, G, B: - Increase the contrast of the image by a scale=1.2, leaving intensity value center=128 unchanged - then lighten the image by offset=+30 intensity levels.

Image 1

Image 2

Question 4: Interactivity - Parameters

Add controls to modify interactively offset, scale, center and threshold.

GUI

Question 5: Interactivity - Mouse

  • Add mouse handling that enables the user to select a rectangular zone (x,y,w,h).
  • The output image should be a copy of the corresponding region from the input image.
  • Make sure the output canvas is resized according to this content.

  • First - Double click where you want to start your crop
  • Second - Just one click where you want to finish your crop
  • Last - crop();