IMAGE PLUG-INS FOR GIMP

1
IMAGE PLUG-INS FOR GIMP

• Author Vera Kukic
• Supervisors Shaun Bangay
• Adele Lobb

2
GIMP

• Overview
• Recap
• GIMP
• Image Plug-ins
• Research
• Algorithm
• Colour Transfer Algorithm
• Image Inpainting Algorithm
• Phases
• Questions

3
GIMP

• GIMP is the GNU Image Manipulation Package
• Open source
• Well documented
• A lot of reference material available
• Easy to use

4
Image Plug-ins

• Colour Transfer between Images
• Transferring colour from a source colour image to
  a destination greyscale image
• Image Inpainting
• Touching up old photos
• Removing unwanted objects/text from images

5
Research

• Research based on
• Transferring Color to Greyscale Images
• Image Inpainting
• Read the papers that were referenced by the
  authors of the original papers
• Mathematics visited the maths department on a
  number of occasions
• Developed strategy and algorithms

6
Colour Transfer Algorithm

• Choose the source colour image and the
  destination greyscale image
• Convert each image to the laß
• Select colour from source image using swatches
• Transfer the swatch colour to the selected region
  of the greyscale image

7
Colour Transfer Algorithm

• Convert each image to the laß
• The laß space was developed to reduce the
  correlation between the 3 coordinate axis of the
  colour space
• l chromatic luminance channel
• a yellow-blue channel
• ß red green channel

8
Colour Transfer Algorithm

• Convert each image to the laß
• First convert RGB image to XYZ tristimulus values
• Then convert XYZ to LMS space
• From LMS space convert to laß space

9
RGB to LMS

• // convert RGB to LMS.
• void rgbtolms (double r, double g, double b,
• double l, double m, double
  s)
• l 0.3811 r 0.5783 g 0.0402 b
• m 0.1967 r 0.7244 g 0.0782 b
• s 0.0241 r 0.1288 g 0.8444 b

10
RGB to laß

• // convert RGB to lab (human perceptual space).
• void rgbtolab (double r, double g, double b,
• double l, double alpha, double
  beta)
• double ll
• double mm
• double ss
• double L
• double M
• double S
• rgbtolms (r, g, b, ll, mm, ss)
• L log10 (ll BLACKOFFSET)
• M log10 (mm BLACKOFFSET)
• S log10 (ss BLACKOFFSET)
• l (L M S) / sqrt (3.0)

11
Colour Transfer Algorithm

• Swatches
• Allow more user interaction
• User can selectively transfer colours between
  corresponding swatches
• Advantage
• Prevent wrong parts of the image from corrupting
  the swatch
• Transfer colour even if two corresponding regions
  vary greatly in colour and luminance

12
Colour Transfer Algorithm

• Transfer colour
• Each pixel in the greyscale image must be matched
  to a pixel in the colour image
• The comparison is made based on luminance value
  and neighbourhood statistics
• Luminance value l
• Neighbourhood stats are precomputed over the
  image
• Standard deviation of the luminance values of the
  pixel neighbourhood

13
Colour Transfer Algorithm

• Transfer colour
• The aß values are transferred once the best
  matching pixel is found
• The original luminance is retained

14
Image Inpainting Algorithm

• Discrete Equation
• Rate of change of I(i,n)
• Estimate Smoothness of Function
• Use discrete implementation of Laplacian
• Compute Change of Value
• Define direction of N (the normal vector)

15
Image Inpainting Algorithm

• Diffusion Process
• Interleaved with the image inpainting process
• Repeated every few steps to ensure the correct
  evolution of the direction field
• Process is repeated until steady state reached

16
GUI
17
Phases

• Research
• Read understand the mathematics behind the
  methods of implementation
• Develop Algorithm
• GUI
• Learn GTK
• Design Interface
• Implement the algorithm
• Test
• Experiments

18
Questions?

• ?