The choice of image format in bitmapped graphics is crucial as it affects file size, image quality, compatibility, and the availability of certain features like transparency or animation. Common formats include JPEG, PNG, GIF, BMP, and TIFF, each with its own strengths and limitations. For instance, JPEG is widely used for photographs due to its efficient lossy compression, which reduces file size with minimal visible quality loss. However, it's not ideal for images requiring transparency or sharp edges, like logos.

PNG is preferred for images requiring transparency and lossless compression, making it suitable for web graphics. GIF is used for simple animations and also supports transparency, but it's limited to a 256 colour palette, reducing its suitability for detailed images. BMP and TIFF are less common, often used in professional environments where lossless quality is paramount. The choice of format depends on the intended use of the image, considering factors like the need for compression, colour fidelity, transparency, and the target platform or audience.

The RGB colour model is central to bitmapped graphics, particularly in defining the colour of each pixel in an image. RGB stands for Red, Green, and Blue – the primary colours of light. In this model, colours are created through the combination of these three colours at varying intensities. Each pixel in a bitmapped image contains values for red, green, and blue, which combine to produce a specific colour.

In a 24-bit colour system, each colour (red, green, blue) is represented by 8 bits, allowing for 256 levels of intensity for each colour and over 16 million possible colour combinations. This model is crucial in digital imaging as it aligns with how digital screens display colour, making it the standard for images intended for viewing on electronic devices. The RGB model is versatile and allows for a wide range of colours, making it suitable for everything from simple graphics to complex photographs.

Aspect ratio, the proportional relationship between an image's width and height, plays a significant role in resizing and cropping bitmapped images. Maintaining the correct aspect ratio is crucial when resizing images to prevent distortion, where the image might appear stretched or squashed. For instance, an image with an aspect ratio of 16:9 should maintain this ratio even when its size is changed, to preserve its original appearance.

When cropping an image, the aspect ratio determines the shape of the cropped area. Choosing an aspect ratio that differs from the original can change the framing and composition of the image. This is particularly important in photography and graphic design, where the aspect ratio can impact the visual impact of the image. In practical applications, many software tools allow users to lock the aspect ratio when resizing or provide standard aspect ratio options for cropping, ensuring the integrity of the image's composition.

Gamma correction is an important concept in bitmapped graphics, primarily concerned with how images are lit and how their colours are represented. It relates to the non-linear manner in which human eyes perceive light and colour. The gamma value, typically between 1.8 and 2.2, is used to adjust the luminance of the image. When an image is captured by a camera or scanner, it is often encoded with a certain gamma value to approximate the non-linear response of human vision.

In computer graphics, gamma correction ensures that the brightness levels of an image are accurately represented on different display devices. Without gamma correction, images might appear either too dark or too bright, depending on the device. Applying gamma correction involves encoding and decoding processes: the image is encoded with a gamma value for storage and transmission, and then decoded (corrected) for display, ensuring the viewer sees the image as intended, regardless of the display device's characteristics.

Lossless and lossy compression are two methods used to reduce the file size of bitmapped images. Lossless compression reduces the file size without any loss of quality. It works by removing redundant information in the image data, allowing the original image to be perfectly reconstructed when decompressed. Formats like PNG and TIFF often use lossless compression. This method is ideal for images requiring high precision and detail, such as medical imaging or professional graphics.

On the other hand, lossy compression significantly reduces the file size by permanently eliminating some data in the image. This results in some loss of quality, which can become noticeable as artefacts or blurring. JPEG is a common format using lossy compression. The level of compression can often be adjusted, allowing a balance between file size and image quality. Lossy compression is more suitable for applications where perfect accuracy is not crucial, such as web images or photographs, where a slight reduction in quality is acceptable in exchange for considerably smaller file sizes.