Saturday, August 30, 2008

Warning - Don't resave and resave your JPG files


New Photographer Tip: Warning - Don't resave and resave your JPG files
Avoid saving and resaving jpg files. Each time a jpg file is changed and saved it is compressed and you will loss image quality. The preferred option is to save your files as TIF files (or PSD files using Adobe Photoshop software) as they are not compressed and you will retain your image quality. To select your file formats in your image editing software select File/Save as/dropdown menu. If necessary use the jpg format as final file save for smaller files.


Enthusiast Photographer Tip -Reasons to Shoot RAW files

Raw files have not had white balance set. This allows one to set any colour temperature and white balance one wishes after the fact with no image degradation. File linearization and colour filter array (Bayer) conversion is done on a computer with a fast and powerful microprocessor versus in the camera. The raw file is tagged with contrast and saturation information as set in the camera by the user, but the actual image data has not been changed. The user is free to set these based on a per-image evaluation rather than use one or two generalized settings for all images taken.

Possibly the biggest advantage of shooting raw is that one has a 16 bit image (post raw conversion) to work with. This means that the file has 65,536 levels to work with. This is opposed to a JPG file's 8 bit space with just 256 brightness levels available. This is important when editing an image, particularly if one is trying to open up shadows or alter brightness in any significant way.


Reasons to Shoot JPG.

Files are smaller and therefore more of them fit on a card. For many applications image quality is more than sufficient (family snapshots, news images). Small files are more easily transmitted wirelessly and online. This is important to newspaper photographers. Many photographers don't have the time or inclination to post-process their files. Many cameras (especially digicams) can not shoot quickly when working in raw mode. Some lower-end models can't record raw files at all.

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