Assignment 1
Image Compressison
My Assignment is contrasting the difference in images when compressed using Adobe Photoshop! The 3 images are display below and how i went about testing them until i reached an appropriate compression
Image 1
For the first image I have chosen I have resized the image to 800 x 600 pixels, the image quality does not change and it makes it a more appropriate size for the web. Ideally it is the best image to use but it is large at 449kb, ideally this should be at least halved so a page won’t take too long to load.
I have tested out a few different colours and used dithering on all of the images, and didn't use dithering on them too to demonstrate the difference. I used a minimum amount of colours which was 2 and 32 as the maximum, i believe you would get away with 32 colours in this particular case and no one could tell unless they were familiar with the original image. The images i have underneath here range from 2 colours to 32 and are labelled.
The first image is 2 colours and does not have dithering, it is only 41kb!
The second image has dithering and is 44kb!
They both are very unclear and need to display colour and this image compression would not be used
The first image here has 8 colours and no dithering, the image is much better and gives more of a painting style to it as it originally is. It is good enough to use in my opinion, you could get away with it. The size is 116kb!
The second image is 8 colours with dithering, there isn't much of a difference evident straight away, but look closely and you see the different shade. The size of the image is 133kb!
I would chose the image with no dithering which is the first one below if i was to use it online, it is the best compressed or such little colours used!
The final two images are using 32 colours, these are better images to use but i feel you could get away with the two using 8 colours.
The first image is with dithering and is 242kb! It is a better image but unless you are downloading the images you can not tell a huge difference between both images.
The second image is without dithering and is 209kb! Again the quality isn't as good but it is still good from the original.
Image 2
I chose this second image because it has large amount of colours so it would be clear of the comparisons. The original gif image is 312kb! I have changed the resolution to 800 x 600 pixels. I will compare the rest of the compressed photo's below to show the difference.
These photos are compressed to 4 colours and as you can see the colour has dramatically changed and is not very good.
The first image is without dithering and works better on the photo and is evident to see if you look closely. The image is 52.1kb and compressed down to a small size from original. It has 4 colours but is pointless to use as this image needs colour.
The second image with dithering is 73.1kb, it is poorer than the first and like the first is still not appropriate to use on a web page.
These images use 8 colours and looks very well for the colours that are in it.
The first image is with dithering and is a much better image t use, i still would not settle with it as a final image. The image size is 106kb! But is not very good to use, it doesn't add as much colour to the image.
The second image without dithering is 73kb! It is very noticeable that it displays a lot more red throughout the image. It is much worse than the first one and compression to this level isn't yet good enough.
The first image here is 32 colours and has dithering. The file size is 165kb! colours and is suitable to use for a web page. This image i recommend should be used for a web page.
The second image is without dithering and is not as clear. The file size is 112kb! it isn't as clear neither are the colours as good.
Image 3
This third image is also 800 x 600 pixels, it is compressed below as i go along and surprisingly needs very few colours. The file size is 335kb! I chose this image so detail might be evident but is not, it is more deceiving.
These images have only 4 colours and are not very clear colour wise.
The first one is with dithering and is better than the second one in this case. The file size is 55kb!
The second image is without dithering and is 38kb! The pixels are more obviously all over the place.
These images are both not appropriate for use!
These two images are both 16 colours and are surprisingly good for thew amount of colours in them.
The first image has dithering and the image size is 117kb! This is very good on colours and could be used o a web page.
The second image is without dithering and is not as good. Pixels are distorted more on this. The image size is 96kb!
The images here both have 32 colours. They are ideal in the amount of colours and you are not missing too much from the original.
The first image is with dithering and is 173kb! The images are both very similar so either are usable, preferably the smaller one.
The second image is without dithering and is 152kb! I think this image should be used on a web page as the colours are good on it and its a smaller file.
Graphs
These are graphs based of the images 1-3! They display the colours and the size of file with and without dithering!
Image 1 Painting
Image 2 Family guy
Image 3 Giants Causeway
In this report i learned that you can dramatically lower the size of an image by lowering the colours and doing some modifations to it to keep the picture quality. This is very useful for putting images on the Internet. It will be kept in mind for uploading images in future!
