This week we discussed digital image management, including image formats, print Vs Screen and image metadata.
Image file formats are standardised ways of organising and storing your digital images. Image files are made up of either pixels and/or vector (geometric) data. however the forma is the files are put into pixels when displayed on most graphic displays.
Pixelated bitmap image Vs Vector image
A rastor graphics image also known as a bitmap,in computer graphics is a dot matrix data structure representing a generally rectangular grid of pixels or points of colour, viewable via monitor, paper, or other display medium. These raster images are generally stored in image files with varying formats.
Files can be saved in compressed or uncompressed file format. Lossless compression algorithms reduce file size without losing image quality, though they are not compressed into as small of a file as a lossy compression file type. if you are looking for a better image quality rather than file size, lossless algorithms are usually chosen.
Lossy compression algorithms take advantage of the limitations of the human eye and discard invisible information. Most of these lossy compression algorithms allow for variable compression levels. As these levels are increased the file size is reduced.
Lossless= smaller file size-no loss in quality
Lossy= smaller than lossless-quality reduced.
- PSD ( uncompressed/ lossless)
Photoshop Document- allows for support for most imaging options available in Photoshop. (layers/ transparency/text etc.)
- TIFF (un/compressed/loss(y)less)
Tagged Image File Format- storing images, used by graphic artists/ publishing industry. Differences in method of encoding, making them difficult to open on PC or Mac.
- DNG (uncompressed/lossless)
Digital Negative- open lossless RAW image format, by Adobe, used for digital photography. Has a greater bit-depth and wide colour gamut. Takes up less space than a TIFF file.
- GIF ( compressed/ lossless)
Graphics Interchange Format- a bitmap image format, introduced in 1987. supports still images and animations and allows a separate palette of 256 colours for each frame. This can give them a distinctive visual quality.
- PNG ( compressed/ lossless)
Portable Network Graphics- a bitmapped image format that uses lossless data compression. an improvement and replacement for the GIF format as a file format not requiring a patent license. They also support image transparency, unlike the JPG’s.
- JPG (compressed/ lossy) & JPEG
Joint Photographic Experts Group- a compressed file type. makes a rasterised bitmap type image. usually a lossy compression, produces small file sizes, allowing for sharing via email, or online. Common file storage format for digital cameras.
Exchangeable Image File Format: A standard that specifies the formats for images, sound, and ancillary tags used by digital cameras, scanners and other systems. This specification allows tags to be added to JPEG, TIFF and WAV audio format. (exif view available as an Add-on for Firefox browser.)
As it contains information about the photo, it can cause a privacy threat. Especially if the photo was taken with a GPS enabled camera, it could reveal the exact location the picture was taken. Luckily the Exif tag can be removed before publishing. (Exif Data Removal)
An image hosting service allows you to upload images to a Website. It then stores the image to its server, and allows others to view that image once they have a special code for the image.