Audio Lab 4

Task 1

Apply a custom filter to the image in the manner discussed in the lecture to filter the image as
Filter > Other > Custom and modify the default mask to :

    -1

-1  4  -1

    -1

The image is switched to a similar fashion as a negative effect that would polarise the colours. The effect is similar to this although it has created the image as a pure black and white image with the highlights and details being left in white and the other colours being changed to black. To be honest I'm not really sure why it changes the way it does although I can guess it will be something to do with the filter changing the pixel values.

Task 2

Experiment with various masks and explore the use of the preset masks in the High pass, Maximum and Minimum options. Where possible describe and explain what you see?

In the first image the intensity of light has been increased however the detail of the image still remains the same. You can still see each individual brick on the clock tower. My guess is that the low frequencies have been altered by the mask effect.

In the second and third images the mask reduces, the second iamge, and increases, the first image. the amount of the colour black in the image. In the second image it is increasing the lighter colours and reducing the number of darker colours. Where as the third image is doing the exact opposite and is increasing the darker shades of light and dulling the lighter colours. I imagine that a range of specific value pixels are targeted and then altered by the masking effect.

Task 3

Suggest possible uses of this filter technique for processing digital photographs?

Possible uses of these effects and masks could be that the High Pass could be used when an image has lots of areas of black you could use the mask to highlight and alter them. Each effect could in their own way be used to smooth out the the pixelation of an image. Perhaps using the High Pass effect could be good to highlight lines in a piece of art. using effects and masks can make an image stand out or from others or even give it an extra edge that was not previously there.

Task 4

Create a new filter that is all zeros except for the center value which should be 1. What does this filter do and why? 
How can you check it operates as you think it does?

The only way to compare that the filter operates as it should it by visually comparing the original image and the altered image. Looking at both images it is clear that nothing has been altered by using the mask. 

Task 5

Create a new filter with a 2x2 matrix with 1's near it's centre. What does this filter do and why?

The mask has brightened the image although some darker colours still remain unaffected. The sky and the lamp glass, being the lightest on the image, have been brightened and almost completely changed to white. Whereas the two stone pillars at the front are still very dark in comparison to the rest of the image.

Task 6

Create a new filter with a 2x2 matrix with +1's on the one diagonal and then -1's on the other. What does this filter do and why?

The image now has been changed in a similar fashion to the first task although it is a more extreme version as the lines and now almost invisible and are hard to see unless you strain to see the smaller details. The values of the pixels have been reversed and altered so that the values are only black and white.