Every image is composed of arrays of pixels with each pixel storing a color intensity value. For the most part, an image is defined by the intensity and layout of its pixels. As was discussed in Module 1, grayscale and colored images are composed of one or more layers of pixel matrices, providing spatial understanding and intensity values. This activity introduces you to the importance of a decent pixel resolution and discusses how obtaining a pixel’s intensity value may be beneficial to analyzing images and image data.
Visualize how pixels are laid out in an image.
Acquire pixel intensity values for colored images.
Explain the importance of being able to obtain pixel intensity values.
Access to a computer and large screen (if you want share with others)
Access and ability to use Google Colab
Writing utensils (pencil, pen, etc.)
Pixel Intensity - The value of a pixel. Pixel intensity is the level of color or brightness that the pixel is representing. Pixel intensity is an important attribute of images when performing image processing and analysis.
Resolution - The ‘depth’ of detail that is available within an image due to the number of total pixels present in the image. As the number of pixels increases in an image, the greater ability for the image to convey smaller details. Resolution can also be used in reference to the clarity of an image. With a larger number of pixels, there are more locations for fine detail in an image.
Pixels are the fundamental unit of images and are what machine learning models use to extract information from an image; the two main parts are pixel intensity and pixel resolution. The intensity means how bright the pixel is, while resolution is how many pixels make up the image.
This means that the more pixels our image has the more data our image has and thus the more information our machine learning model can extract from the image. This is why larger resolution images look smoother since there are more pixels to convey the visual information of the image.
However, this also means that it will take more resources and time for a model to look through a higher resolution image compared to a lower resolution image, since it has to go through more information. This is why finding an optimal compromise between pixel data compared to model learning speed is an important aspect of machine learning. If you are using a large data set such as cats for example, you don't need as large of images since the model will be looking more for the general shape of a cat rather than the very fine details, however, if you instead are trying to look at what species of cat then an increase in resolution may be beneficial to extract more fine details to get the species.
Ensure that the Image Processing Image Dataset folder (from Module 1 Introduction) is uploaded to your Google Drive as detailed in the Google Colab Interaction Guide.
Read and work through the All About Pixels - Handout and the corresponding All About Pixels - Colab Notebook.
Work through the All About Pixels - Knowledge Assessment, you will need the All About Pixels - Colab Notebook.
There are multitudes of available resources to assist in furthering your understanding of the concepts presented in this activity. The resources listed below are here to help you get started.