Representing Images – Data – GCSE CS

Images are an important part of modern digital media, and they are used in a variety of applications such as websites, social media, and mobile apps. Understanding how images are stored on a computer and how to calculate their file sizes is crucial for anyone who works with digital images. This blog post will provide an overview of images on a computer and the methods used to calculate their file sizes.

Images on a computer are stored in a variety of file formats, such as JPEG, PNG, and GIF. Each file format has its own set of advantages and disadvantages, and they are best suited for different types of images and applications. For example, JPEG is best for photographs and images with many colors, while PNG is best for images with transparent backgrounds or small icons.

The file size of an image is determined by the number of pixels it contains, the color depth, and the compression used by the file format. The number of pixels in an image is represented by its width and height, measured in pixels. The color depth is the number of bits used to represent the color of each pixel. The compression used by the file format is the method used to reduce the file size of the image.

To calculate the file size of an image, you can use the following formula:

File size (in bytes) = (Width (in pixels) x Height (in pixels) x Color depth (in bits)) / 8

For example, if you have an image that is 800 pixels wide and 600 pixels high, with a color depth of 24 bits, the file size would be:

File size (in bytes) = (800 x 600 x 24) / 8 File size (in bytes) = 1,440,000

This result is in bytes, if you want to convert it to a more human-readable format, such as kilobytes (KB) or megabytes (MB), you can use the following conversions:

1 MB = 1,048,576 bytes 1 KB = 1024 bytes

So, in the above example, the file size would be approximately 1.37 MB.

It’s also important to note that, the file size of an image can be reduced using compression, the most common method of compression used in image file formats is lossless and lossy. Lossless compression reduces the file size of an image without losing any quality, while lossy compression reduces the file size of an image by discarding some of the image data, resulting in a loss of quality.

In conclusion, understanding how images are stored on a computer and how to calculate their file sizes is important for anyone who works with digital images. By understanding the different file formats, the number of pixels, the color depth, and the compression used, you can determine the file size of an image and make informed decisions about how to optimize and manage your digital images.