There are many ways to save a file format from a picture file. Which digital format should you use when choosing a format over another? There are literally thousands of digital cameras that range from the consumer to professional digital camera on the market today. Each touting to have more mega-pixels than the other. My personal digital camera choice right now is Canon EOS cameras until I can afford the Leica brand…..if ever!
JPEG (.jpg) – compresses photos by discarding pixels determined to be unnecessary. A 24 bit image saved as a JPEG file can be reduced to one twentieth its original size. JPEGs, with their smaller sizes and faster transmission time, are the preferred methods of displaying images on the Internet, websites or sending digital images over the Internet and email. All digital cameras offer this format as a file option. JPEGs can be saved in various sizes. The more compression reduces the file size and image resolution when printed. It is best to take images in the biggest format when possible, therefore attempt to purchase the largest card possible to save digital images. When opening a JPEG image, changing it and saving it degrades the image. Each time the image is compressed, it loses quality. After you open the JPEG from a digital camera, save it as a TIFF or PSD files so you can open, change and save it again without losing quality. Save the picture as JPEG only if you need space or transmit the image over the Internet. Adobe Photoshop images are PSD files than can be saved as JPEG images.
TIFF (.tif) – the universal format for high quality photographs and be open on any computer by nearly every program that works with photographs. It is the widely used format for publishing and printing. Saving a file as a TIFF makes no changes to it, or its original compression (LZW) is loss-less.
PSD (.psd) – Adobe proprietary format for Photoshop documents. PSD files can be opened and edited only in Photoshop. If you use Photoshop to edit a file, there are a few reasons to use any other format until you editing is complete and you save the file for a specific purpose.
Camera Raw: .CR2 and .CRW (Canon), .NEF (Nikon), .PEF (Pentax), .ORF (Olympus), .3FR (Hasselblad), etc. – Raw files are a direct representation of an exposure on a camera sensor. No captured data is lost. A camera raw file saves individual photosite data (Each captured pixel represents one primary color.) in its full bit depth. White balance are saved with the file but pixel values are not changed by them. Raw file formats are proprietary; each camera manufacture has their own. Most camera raw files can be opened in Photoshop and other applications and resaved in a different format.
DNG (.dng) – is a camera raw format that is open source, which meany any camera or software company can use it in their product. Any other camera raw format can be converted and kept intact with the DNG shell.
PNG (.png) – is a loss-less compression format used for web based photos. It interlace images and display in the browser with up to 256 colors.
GIF (.gif) – produces small Web files and is best for flat color images with type or line drawings included. Not good for photos.
EPS (.eps) – can save photographs, illustrations, and text together. It is primarily used in publishing but rarely used in other fields.
BMP (.bmp) and PICT (.pct) – platforms specific graphic formats: BMP for Windows and PICT for MACs.
How to determine which format to use when saving an image guideline:
- If animation is required.
- Line drawings and simple graphics.
- Photos, especially without high contrast.
- Screen-shots, especially of movies, games, or similar content.
- Line art, illustrations.
- Photos with high contrast.
- Transparency, especially alpha channel transparency.
- Application screen-shots or other detailed diagrams.
And here’s an overview of which formats to avoid for each type of image:
- Images with gradients.
- Images with high contrast.
- Detailed images, especially diagrams.
- Simple graphics (the file sizes are larger).
- Photos with low contrast.
Keep in mind that the megapixel size of a camera impacts the maximum size of the prints that can be made. One reason to choose one format over another is to reduce files size. Larger image files take longer than smaller files to save, open, and transmit, and they use more file spaces to save. Image files can be compressed.