1. Enhancing the Enlargement of Images
Tara Naughton
Computer Systems Lab

2. Introduction Typically two methods of image enlargement
Pixel replication
Replaces original pixel with group of pixels of the same value
Interpolation
Replaces original pixel with group of expanded pixels
Produce results too jagged or too blurred

3. Fig 1. Pixel replication vs. interpolation

4. Fig 2. Original image
Fig 3. Zoom by pixel replication
Fig 4. Zoom by interpolation

5. Similar Research Focus on keeping defined edges Ramp edge model
Locate edge pixels, derive parameters, derive intensity, keep parameters the same in the enlarged images
Step edge model
Divides image into “atomic areas,” derive step edge parameters for each pixel, find intensity of atomic areas, find step-likeness value to see if near step edge, use step-likeness value as weight to combine intensity values derived for atomic area
Fig 5. Step edge parameters
Fig 6. Ramp edge parameters

6. Background Coding in Python Takes input of black-and-white .pgm images
Outputs enlarged black-and-white .pgm images

7. .pgm images Portable graymap format Gray-scale image
Explains the type of file (P2 for PGM)
Width and length of image
Range of intensity values
Intensity
Values of
pixels

8. Discussion Separates images into parts: edges and non-edges
Resize non-edges with interpolation method
Find intensity values for edges and resize accordingly
Equation that takes multiple variables into account, including edge value
Produce images neither too blurred or too jagged
Compare between original, resized image, and image resized by other methods

9. Results Pixel replication and interpolation methods completed
Algorithm to identify edges completed
Complete interpolation algorithm including isolation of edges being toyed with

10. Fig 7. Original image
Fig 8. Image resized by pixel replication

11. Fig 9. Image resized by interpolation
Fig 10. Edges of interpolated image

12. Future Research
Algorithm could be developed further to improve quality
Work with color images and other file types