Best Format to save photos

[loujul]

I read recently that when you scan photos you should save them as .tiff to preserve the quality and only use .jpeg to send over the internet. Is that true and does that apply to photos I download from my camera to my computer? Should I be saving all of them as .tiff. Also the article read that once you save as a .jpeg you cannot save it to a .tiff. That doesn't make sense to me. I need some expert advise.

[Wendy]

Hi ...

When you download from your camera it probably saves then as jpgs ... now if you are not going to work on them then just leave then as they are. That won't hurt them ...

If you are going to do work on them then save then a .psd files until you have finished and then decided if you will need any of the layers again and/or if you are going to do more work on the images.

If the answer is yes then save then as .psd files ... but if the answer is no and they are not special images then I would tend to save them a best quality jpgs :)

Most of my photographs are finally saved as jpg ... its only my layered creations that I finally save as psds :)

Wendy

[Byron Gale]

...I need some expert advise.loujul,

Here's some amateur advice until an expert comes along... :p

JPG is a compressed image format. It is "lossy", meaning that when the image is compressed to make the file size smaller, some of the image data is permanently lost. The algorithms are designed to make the losses in less-noticeable areas, but they are there, nonetheless. To many, this is an acceptable trade-off, because the JPG image looks good to them, and they get a more manageable file size. To many others, this is worrisome, because they want to preserve all of the data possible.

TIF and PSD are non-lossy image formats. That means that every pixel is preserved between open-save-close-open cycles.

If you have your camera set to save images as JPG, your camera is actually taking the raw image data from the sensor, and compressing it into a lossy JPG file... so you lose image data before you ever see the image. Again, some are OK with this, while others opt to have their cameras save in RAW or TIF, accepting the larger file sizes as toll for "whole" images. (Some cameras don't offer an option, so the point is moot for those photographers!)

Most people will be satisfied with the appearance of a JPG image! The main problem will be if the same JPG image is opened-saved-closed multiple times -- because then the JPG losses begin to compound, and the image can become visibly "injured". (There is no problem with looking at the image as much as you want - it is the saving that causes it to be re-compressed... )

There is no improvement in quality to simply re-save a JPG as a TIF or PSD. So if your camera gives you JPG files, those files have the best "fidelity" your images will ever have - so there is no need to convert them to anything else. Unless you want to edit them. I think most will agree that a good way to proceed would be to open the original JPG file, then save as a PSD or TIF file with your edits. (Because PSD and TIF are non-lossy, quality will not deteriorate as you edit and save the files - as many times as you like) Then, if you need a copy of your edited file to email or post to the web, or send to a print shop, you make a JPG copy of the edited file. This way, you only suffer one generational compression and will likely be unable to detect any problems with the image.

As far as scanning - again, I think most would agree that a good way to proceed would be to save the initial scan as non-lossy PSD or TIF. Then make JPG copies as needed, the same as a camera image.

I hope you don't come away thinking that JPG is horrible - it is not. It is a compromise between image size and quality. Whether that compromise is acceptable to you is for you to decide.

I'll shut up for a while and wait for the holes in my explanations to be pointed out!! :D

Byron

[Jeff Perry]

Loujul, depending on the type of camera you have, it records the images onto your memory card as JPG, RAW and or TIFF. Some high-end DSLR cameras will do all three,many bothe JPG & RAW at the same time. Point and shoots always give you at least JPG and some may allow saving as RAW. Remember this is all in-camera stuff. Once saved tothe memory card you then download tothe computer saving to the hard disk in whatever format they were stored in on the memory card.

After that's it is up to you depending upon what you are doing with them. When editing in PS or PSE at the point of saving your work, you have dozens of formates to save them in, the most logical is PSD to preserving the working status, e.g., layers, etc., of your file, or as a multi-layered TIFF, or as a flattened JPG (all the layers are combined into one). the latter is not usually done until you are reallllly done editing twyour work, and you want to e-mail it, etc.

The RAW format is native image capture from the camera's sensor in its purist form, and many people always record their images in RAW, to be processed later in-computer (and saved to something else). And ALL RAW images need to be processed/adjsuted/enhanced in order for them to be of any presentable quality.

The JPG format, has already received that inital processing in-camera before it is saved to your memory card. Once moved to the computer and opened, edited in PSE and then resaved, during the saving process applications use a compliant JPG compression process to give you a near-perfect duplicate (some people will argue with the "near-perfect" claim) of the original but with a lot less "air" and much more compact. As an example, a 4MB JPG image right out of the camera, can often be compressed to 400KB with little or no degradation visible to the naked eye when printed. One of the more serious problems with JPGs is that each time you edit and re-save, there is more potetnial for degradation over time, sort of like compounding. The advantage is the open format and the size is ofeten hundreds of times smaller when compatered to RAW and TIFF.

TIFF is a good working alternative to PSD, and when saved is considered "loss-less" which means the saved copy is EXACTLY like the original, bit for bit. It too is an open format like JPG, and is understood by most good software applications.

Decide up front in what format you want to capture your images "in-camera", then once moved to the computer, process and save in the format that best suites your needs and circumstances.

Hope this helps.

Jeff

[loujul]

Thank you all for your advice. I understand now the difference among the extensions and will be able to make my choices correctly. Thanks for your expertise!!!