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Image file type
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| File Type |
Extension |
Compression |
Bit Depth |
+ |
- |
| JPEG |
.jpg |
JPEG uses a lossy form of compression based on the discrete cosine transform (DCT). |
8 bit |
Small File Size – Ideal for web use and email.
Varying rates of compression reduce file size further, at a cost of loss of original image quality
Recognised file format on all computers as well as displaying on digital photo frames, mobile phones, DVD players etc.
Ideal for small prints such as instant photo booths.
Can embed colour space profiles as well as ITPC Metadata |
Lossy compression, as the file is compressed to save space, it loses some of the original file data and therefore degrades image quality
Further editing on the image can degrade quality even further.
Only suitable for smaller print output, as on larger images, compression artefacts and noise can be present on final print. |
| Portable Network Graphics |
.png |
PNG uses a 2-stage compression process:
pre-compression: filtering (prediction)
compression: DEFLATE |
1,2,4,8 bit |
- minimum compression loss. The image quality is not changed by any compression ratio;
- format is suitable for storage of intermediate versions of the image. When you re-save image, quality is not lost;
- PNG supports a large number of colors. PNG-8 (256 colors) and PNG-24 (about 16.7 million. Colors);
- it supports multi level of transparency. Image has the 256 levels of opacity from fully opaque to fully transparent;
- it’s possible to work with layers;
- the ability to add to the file meta-data;
- small size files. |
- doesn’t support animation;
- ill-suited for working with full-color images;
- can not store multiple images in one file; |
| Graphics Interchange Format |
.gif |
is a bitmap image format |
1-8 bit |
There are several advantages to using animated GIFs and the first is that they have relatively small file sizes; this means that they can be used easily online as they can load quicker and still have a good quality.
As well as small file sizes GIFs also support transparent backgrounds and therefore can help show a professional look to a website with an animation over a different background.
Another advantage of GIFs is that can show something in a better way than would normally be possible as they can show emotions and movement which a still image may not be able to, this might also be helpful when creating tutorial animations. This also ties in with the fact that using GIF files can entice different, younger audiences as the children may be amused by these animations. |
Although animated GIFs have advantages they also have their disadvantages as they only have a maximum colour palette of 256 colours so therefore can sometimes look of a poorer quality than other types of file or image. This can lead to the images having more ‘blocky’ colours and also looking slightly pixelated.
Another disadvantage of using animated GIFs is that once the animation has been coded into the actual GIF file there is no way to go back and edit the image. This may lead to having to start all over again to make a minor adjustment to an image.
Although these images have small file sizes and therefore should run smoothly online they are also dependant on internet connection and could lead to the site they are used on looking less professional. |
| Tagged Image File Format |
.tif |
LZW or ZIP |
8 or 16 bit |
Uncompressed image retains maximum amount of image data from the camera.
Can be compressed to reduce file sizes using mathematical algorithms such as ZIP or TAR without loss of image data
Can also use lossy compression such as JPG algorithms to reduce file size
Recognised format by most computers, cross compatible with both MAC and PC’s
Standard format for printing either at home or dedicated Photo lab.
Can embed colour space profiles as well as ITPC Metadata |
Large file sizes, around 20mb for a 10 megapixel image, so larger storages devices needed for long term archival use.
Good specification computer needed to process and load images.
Most website and online images galleries do not support tiff uploading.
Slow speeds when transferring to online galleries that do support TIFF files |
| Portable Document Format |
.pdf |
Select PDF files from your computer or drag them to the drop area. You can upload up to 20 files at a time. Wait until the PDF compression is completed.
Download each file individually, or you can download all of your files at once in a ZIP archive |
1,4,16,24 bit |
- popularity of formats. PDF can be opened on any device with any operating system in exactly the same form in which it was created;
- easy for viewing. Adobe Acrobat Reader is often pre-installed on your computer and it is totally free;
- PDF takes little space on your hard drive, because it supports a variety of image compression algorithms;
- user can customize the security settings, for example, prohibit printing or editing. Format allows using electronic signatures to determine the authenticity of the document. |
- it’s not free to edit PDF files;
- it’s easier to edit files in other formants than in PDF, because PDF files must be edited in specialized programs;
- it’s difficult to work with text in PDF files, because they are perceived as a picture. |