Posted 04 April 2003 - 12:44 PM
Hi Ralph2I started the digital division of a large professional photo lab in Memphis a few years ago. Growing with digital through the last couple of years, we get this same question from a lot of our customers.From our experience, camera resolution and the image processing algorithms used are far more important than whether the file is saved as a JPG or RAW or TIF. Part of the confusion comes from calling JPG a lossy format. It does lose picture information. However, it loses information ONLY when changes are made to the file then saved again as a JPG. The situation is similar to making photocopies. If you take a high quality original and copy it , the copy never looks quite as sharp and crisp as the original. But as long as you use the original to copy from, all the copies will be identical.IF, however, you copy one of the copies, those copies look much, much worse.The same process works with digital images saved as JPG. You take a picture with your digital camera and it saves it as a JPG. You then transfer the JPG to your hard drive by dragging it from the camera folder to your computer. The JPG that resides on your hard drive is EXACTLY the original image. It is a bit for bit copy of the file. Bit for bit copying will never result in reduced image quality.If you use Photoshop or other program to open the JPG from your camera , then save the image to your hard drive , you have now made a copy of a copy. Why? Because, the JPG format is a lossy format that compresses files by removing ( reducing ) information. By doing the FILE - SAVE from within a program , you have compressed an already compressed file.As an aside, if you open the JPG in Photoshop or whatever, print it on your inkjet, then CLOSE ( not SAVE ) the image, you have done nothing to the original file.Lastly, if you have images that you know that you will do correction work on , open the JPG in something like Photoshop and SAVE a copy as a TIF. Do all your corrections on this TIF and leave the original JPG untouched.Sorry this was so wordy, but I hope I answered your concerns.BTW, the Canon cameras take excellent pix. Likewise the Olympus 4000 & 5000 series.For more professionally geared photographers, the Olympus e-20 and Fuji S-1 / S-2 are unbeatable for picture quality.