Discuss the impact that file format, compression techniques, image resolution and color depth have on file size and image quality

Introduction:
Within this report I will be discussing how learners can use different file formats, different compression techniques, and also various image resolutions also different color depths, I will also display the final sizes and the differences between them furthermore I will also mention jped, psd, bmp, gif and tiff as different file formats.

Photoshop file:
The first format which I will discuss about is Photoshop format also known as PSD, this format is also the default format for this software their fore it will automatically save the edited graphical images to this format unless chosen otherwise.
This format enables you to be directed straight to Photoshop and also grants you permission to use any features of the software, On the other hand the main problem is that you are only ably to open this file with Adobe Photoshop and the file is also relatively large so it may require a lot of space within your computer.

Bitmap File:
Bitmap images are stored in a format which is known as BMP Format. These sorts of images are built up of loads of small squares arranged in a certain way in order to create an image in a similar way photographs are captured. The file size is also directly affected from the resolution of the image, in other words, If the resolution is high the file size will be larger, In my opinion the main disadvantage of this file format has got to be when enlarged the quality/sharpness of the image is reduced significantly

Graphics Interchange Format
This is also known as GIF, it Is what’s known as an compressed image file format, GIF images use a compression formula which was first developed by CompuServe, which in why most cases people see the term “CompuServe GIF” in Photoshop. GIF’s are decided on indexed colors, which could be up to 256 colors. This also helps in order to reduce their file size. These compressed image files are able to be very easily sent over the network/Internet. Which is why you often see them on web pages? Gif files are very good for small icons such as a logo, but they lack the color range for them to be used for any high quality photos.

Joint Photographic Experts Group
This is also known as JPEG, The .Jpg file extension is assigned to image files. Many photographs and interment graphics are stored in the JPG file format.
JPG Files are commonly referred to as JPEG images. Many Bitmap images are saved in .JPG format in order to compress the files, this makes it easier to transfer or download the files and use them on the internet.
The JPG file format is based on a 24-Bit color palette; however these files do drop information when they are decompressed, The higher the rate of compression was when the Jpg file was created, the more the quality of the image will be affected then the file is decompressed.

Tagged image file format: This is also known as TIFF and is a standard image in the printing and publishing industry. TIFF files are much larger than JPEG files, and they can also be either uncompressed or compressed using lossless compression. Unlike JPEG. TIFF files can have can have a bit depth of either 8 bits per channel or 16 bits per channel. You can also store multiple layered images within a single TIFF file.

Compression techniques there are two categories of compression techniques used within digital graphics, lossy and lossless. Whilst each uses different techniques to compress files, both have the same aim. To look for duplicate data in the graphic and use much more compact data representation.
Lossy and lossless each has carious methods which are used be different file formats and achieve different results. Therefore not all lossy or lossless formats will use the same methods. It is beyond the scope of this unit to look at these methods in detail so you will not be assessed on them.
• Lossy compression methods include DCT (Discreet cosine Transform), Vector quantisation and Huffman coding
Lossless compression methods include RLE (Run Length Encoding), String-table compression.
Image quality and resolution
The resolution of an image is decided by the number of points that make up the image, that can be depending on the pixels in that specific image on a monitor screen, or the number of dots that make up a printed image so the more points that are used to create an image, the better the quality and detail of the image will contain.
In other words the resolution of any image is directly related to the file size, if it small then we know the quality of the image will not be as good but if the file size is large the quality will surely be better. The only possible disadvantage which could possibly come from having a larger file size is it may take a lot of space up within your hard drive, however it ,might be very important to have a good quality image, therefore it wouldn’t matter if you were to take up a lot of space. Let’s say you needed the image to be good quality because it is the front cover for a magazine.
Colour depth:
Colour depth is a way to describe the maximum amount of color which is used in a single image, in other words the more colors in the image the more detail the image will appear to be. There are a various amount of color depths such as monochrome, which is the simplest color depth, the color depth also affects the final size of the image, as in resolution, I Will now list different color depths:
32 Bit Colour (True colour) – This color depth is known to many as what you would call “True color” This format has the ability to store transparency information for each and every single pixel. This is for the 256 pixels to be fully opaque to fully transparent,
24 Bit Colour- This format stores the red, green and blue for each pixel, In another definition 256 values for each colour which gives a total of an outstanding 16,177,216 colours (256x256x256). Due to the fact there is a possibility of 16 million colours most likely every quality of an image is to be realistic and to also be very high quality due to the fact the colour depth is higher and there are more colours this requires the storage space to be even higher.
16 Bit Colour – The two bytes which this format uses is one byte for the colour and the second byte which is for the shade of the colour. There are a total of 65,536 colors, (256x256)

As we can see colour depth is vitally Important `when it comes to creating a good quality image but it also effects the size of the image, This means the better the colour depth the larger the size of the file, but it also means the image will consist of much more detailed colours so we should be seeing a much more realistic image.
Conclusion: As we can see from the colour depth section of this report is very clear that some file formats are much better in the terms of graphics and web pages then others, Also different file formats have their own characteristics such as file size, file compatibility, Image quality etc… Compression techniques may also come very handy if you ever wanted to make the size of an image smaller. However it is very important to know which technique affects the quality of the image and which one does not as much. When discussing the resolution of an image or the colour depth, it is vital to bear in mind that the image may get affected in some form, let’s say you were to decrease the resolution, the size of the file will also be smaller, but the quality of the image would not be as good as expected. This is similar with colour depth, the better the colour depth the better the final quality of the image will be but also the higher file size it will be too. In addition I’d say in my opinion I think it is very important to know the effect of changing an image in any sort of way.