The Pixel Explorer and the Mask Applicator
This combined simulation activity allows you to explore pixel values in an image, and the way in which convolution masks change those values. This is basic 'pixel group processing' - the masks can be created, saved and loaded in Adobe Photoshop as 'custom filters'.
The sub-activities are as follows:
- Pixel Explorer: You will explore the RGB values of pixels in an image. As you move the mouse over the image, the immediate area will be shown in close-up, and the RGB value of the pixel immediately underneath the pointer will be displayed, along with the RGB values of the neigbouring pixels. These are the values that will determine the new colour value of a pixel when a convolution mask is applied to it.
- You will click on the image to select a pixel to be processed. The Pixel Explorer will show you its RGB values along with those of its neigbours. You will be shown a specimen convolution mask that will average all of the pixel values to produce a new colour .
- The Pixel Explorer will step you through the workings-out for the particular pixel you've chosen, highlighting each RGB value as it goes.
- You will then be invited to drag the specimen convolution mask and drop it onto the centre of your 9 pixel values. When you do this, the calculations which the application of the mask will produce - that is, the multiplication of the RGB values underneath the mask by the weightings on the actual mask - will be displayed. You can then click on a button to perform the detailed calcuations, and see how the value of the processed pixel is reached. You can repeat this process with different pixels and values until you understand this process. Practice makes perfect!
- The Mask Applicator invites you first to apply common sharpen and blur masks to the image - and then to enter your own custom masks. Make sure your mask values add up to 1 or 0. When you apply the mask, it will process all the pixels in the image one by one. This may take the Mask Applicator a few seconds, so please be patient!
Go to the Convolution Mask Simulation Activities.