OS Computer Settings!

 It's important that you know the extension of your photographs

Mac and Windows OS's by default hide the 3 letter file extension for all files... You need to know what they are as the extensions are part of the filename and is needed by ALL browsers so they knows what to do with the file... Here's how you set that up
On Windows XP
On Windows Vista
  • Go to My Computer and choose Organize > Folder and Search Options
  • Select the View tab and deselect "Hide extensions" for known file types
  • Press OK.
On Windows 7
  • Open an Explorer window and choose Organize > Folder and Search Options
  • Select the View tab -- and deselect the Hide extensions for known file types
  • Press OK.
To see the above with pictures and arrows go to Indezine.com

Making Extensions visible in OS X (Mac)

open the Finder, then choose
Menu
Finder > Preferences
Choose the Advanced Tab
Check the Show all file extensions box







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Understanding File Formats

All files on a PC need to have a three letter extension that tells the computer the nature of the data,whether it is an executable program (.EXE), or a picture file, for example like:

pic-01.jpg pic-02.tif pic-03.raw pic-04.dng


There are many picture file formats, but digital cameras save picture data generally in either .raw, .tif or .jpg formats. The extensions can be written with upper or lower case letters.

Rule #1: Never throw away data!
Always use the camera or scanners largest resolution --as measured in pixels, with the least amount of compression.

Most consumer Digital Cameras save the picture data only in .jpg format.

A comparison of file format sizes...

File Format Sizes


JPEG (.jpg)

An 8bit, Lossy Format for transporting images over the internet.
Joint Photographic Experts Group - The name of the committee that designed the standard image compression algorithm. JPEG (.jpg) is designed for compressing, either full-color or grey-scale digital images of "natural", real-world scenes, to save space on the computer and for internet transmission time. It is a "lossy" type of storage because even in its highest quality mode the compression scheme throws away data --Every time you save the file!

TIFF (.tif)

An 32-bit CMYK or 24-bit RGB image --Tagged Image File Format -
An uncompressed image file format that is lossless and produces no artifacts.Tiff files can also preserve Photoshop layers.

PSD (.psd )

32-bit .PSD "Photoshop Document file."
A PSD file stores an image with support for most imaging options available in Photoshop. These include layers with masks, color spaces, ICC profiles, CMYK Mode (used for commercial printing), transparency, text, alpha channels and spot colors, clipping paths, and duotone settings. Photoshops version of the .tiff format! Recommend use of the .psd file format rather than .tif

RAW (.raw)

raw dataA 14 or 16 bit / channel Linear data file that contains the raw unprocessed data
It is the data imaged by the camera or scanners sensor usually at 12 - 14 bits per channel! Most raw files use a lossless compression routine that is applied to the data to reduce file size without compromising quality.


DNG (.dng)

Adobe Digital negative. Designed for Raw Digital image preservation (sometimes known as "archiving"): to be suitable for the purpose of preserving digital images as an authentic resource for future generations.

To Date there are over 300 raw file formats

Type of File Format dictated by intended use!

RAW

Use "Raw" if you are serious about your photography and if it's a "money" shot (aren't they all?) ! The linear data gives you headroom of about 2 f/stops, choice of white balance, and more...

DNG

>Recommended use... to store or archive your "keeper" images. Adobe provides a free converter.

DNG Download Mac
DNG Download PC

tif or .psd?

Use .psd if you need to save layer information and have an rgb or cymk file.

JPG

Use may use .jpg if you are shooting for the internet, or you only intend to make small prints up to 8 x 10 or you are going to hand the photo off to a client, as processed in the Camera. However, always use the highest or super fine quality....

Caveat. Every time a picture is saved in .jpg format, data is lost, as a result the compression artifacts get worse... as demonstrated below...
Jpg Compression artifacts

Sample of JPG Compression Artifacts


High Quality JPG Image Uncompressed TIF image

Comparison of Compressed jpg and uncompressed Tif File

Multiple jpg compression

Note the JPG banding in the clouds

If you shoot jpeg photos ---Set the in-camera Color Space (Gamut)

       
                1. Raw files automatically save a linear form of the ProPhoto RGB gamut.
         If you save jpeg files in your camera set the color gamut to       
                FIRST.  Adobe RGB
                SECOND. sRGB  
                        (sRGB is the Color gamut for modern monitors 
                         ---Most consumer cameras automatically default to sRGB)

Always choose the largest color gamut available for your camera, however some cameras use only sRGB as a pre-set. You can determine what color space is preserved in your photos by looking at your cameras EXIF data

In Photoshop the menu item is
File > File Info... Camera Data
You can also look at the EXIF Meta data in the Adobe Browser or Bridge or Lightroom under the Meta data Tab.