When I edit iphoto, I use Elements. When I open get info on an initial photo it may state something like 2.7 MB. However , when I want to resize the image it may state the image / pixel dimension is 20.3 MB. Of course when I resize the photo goes to 2.1 MB. Why the discrepancy?

Assuming you're working with JPEGs, they are compressed once saved. While they are open in PSE, they are uncompressed.

so iphoto does the compressing and/or saving them as jpegs. Chuck made mention to me about 10:1 compression ratios ????????????

is that why some pics that I resized in the past have actually been reimported back to iphoto via PSE as a 780 KB pic when it started out as 2.9 MB photo?

Jan asked me to post this:

When you set the “quality” slider upon closing a JPEG file in an application, you set the compression ratio. If the compression ratio is 2:1, a 10 MB file will be stored in a 5 MB size on the hard disk. If the photo comes directly from a camera, you don’t have much choice in the compression ratio (if anything, typically "high" and "low"). In applications, I don’t know the relationship between JPEG “quality” and “compression ratio.” It’s unknown. In general, JPEG’s are a very poor way of storing photos, since they destroy detail and color permanently . There’s no such thing as a “free lunch.” You're trading less storage space for photo detail that can never be recovered.

Use JPEG’s only if you don’t care about the photo quality. How do you know if you don’t care about a photo ahead of time? You don’t. If you're shooting 99 year old Aunt Emma in the nursing home with her great granddaughter from the Andaman Islands, while she's blowing out the candles on her birthday cake, if it's a special moment that won't be recreated, it's probably worthwhile to spend extra effort to try to take a good photo. It's not that hard, and you can start by not using JPEG's.

JPEG's also destroy edge quality where there are hard edges in photos. See if you can tell which part of the illustration below was saved as a JPEG. [ Hint: look for compression "artifacts." ]

Use only RAW or TIFF file formats in your camera. You don’t have a choice if you are using a phone camera.

If your camera only allows you to save images as JPEG, just make sure to capture the highest quality possible. Obviously, while shooting images, RAW or TIFF is ideal.

From an editing standpoint, once the original image is opened in Photoshop (hopefully Elements allows this also), immediately save it as a Photoshop file (.psd) or a layered TIFF. Do your editing to the image, save it. Flatten the layered file, and resave it as a JPEG, if that is what is desired. Keep the original .psd or .tif for any future editing. Both formats retain quality and do not degrade the image.

JPEG is a "lossy" format. Anytime you save an image as a JPEG, you are losing quality (and you can't get it back). Resaving a JPEG, as a JPEG, further degrades the quality. Photoshop (.psd) has no compression - and is "non-lossy" - meaning that you don't lose any quality. TIFF or .tif format has a compression scheme that will reduce the file size without any loss of quality (non-lossy). It's called LZW. This is an option for saving a .tif from within Photoshop. I'm not sure if Elements has the same option.

so my sony cyber shot does not have the ability to switch from a jpg to tiff or raw. So i set the pics to 7M. Now will iphoto subtract from that 7M photo since it imports as jpg.????

It depends on the operation(s) you perform with iPhoto.

Simple operations - no degradation of the JPEG (adding date, location, EXIF data, header data, maybe rotations).

Complex operations - yes ( colorspace conversion, filter, crop, effect, red-eye, retouch ).

The loss occurs as you save and do the compression. So once you open the file in Elements, you need to do as Mike said and save as a PSD to preserve what you already have. If you make changes and save back as a JPEG then you will lose detail, but if you make changes and save as a PSD (and if you need to export, as a TIFF with LZW compression) then you won't lose anything over what was originally saved.

Since JPEG is a lossy format, you lose detail and quality "each" time it's saved as a JPEG. It degrades the image more, each and every save. In some instances, you can get away with opening a large JPEG, and re-saving as a JPEG one time.

Another thing to be careful of, is upsampling an image (enlarging its size or increasing its resolution). Upsampling is never really recommended - though you can upsample slightly, without too much degradation (depending on the image). If for some reason, you wanted to print an image much larger than the original, there is a 3rd party plug-in for Photoshop that does a pretty decent job of upsampling. It's called Genuine Fractals. Off-hand, I don't know if the plug-in is compatible with Elements.

Genuine Fractals is available for PE. In fact, I received information in the box when I purchased PE 6. I think it limits the maximum expansion though, so it does not expand to as big images as GF for Photoshop.

Listen to Mike, and give the digital process a little more thought.

Everytime you alter the photo data, by some operation, you degrade the image. Altering the image header information doesn't change the image data, but it may change how it looks on screen (as when you change the embedded color profile from Adobe RGB to sRGB).

Some operations are reversible in applications with a "history" function (not iPhoto unfortunately). But once you save the photo, or exceed the length of the history queue, you've altered the photo for good. That is to say, you've irreversibly degraded the original image, even if it looks better - it's still not the original. (Actual) colorspace changes, file type changes, uncompression and recompression, filters, cropping, layering are generally irreversible processes. I'm not sure how various JPEG algorithms work, but rotations might in some instances alter the image also. The general idea is to maintain a RAW photo in its original state as long as possible, and only modify it when you're ready to use it for some purpose (like printing). If you display the image on the Internet in "web safe" colors, it will take another hit in image quality. TIFF's can be lossless (and are 99% of the time), and so can PSD files. Anything else causes an irreversible loss.

There is an immediate loss of detail and color in cameras that only output JPEG's. El-cheeso cameras alter an image even before the image leaves the camera and before you move it into your computer.

I didn't what to get too technical originally, but read the website below:

Impulse Adventure




A photo of a flower selectively compressed with progressively more lossy JPEG compression ratios left to right.

This message has been edited. Last edited by: Chuck M,

will iphoto accept psd photos or does it change them to jpgs???? and also lose quality?

quote:

When I edit iphoto, I use Elements.

??

Your very first sentence is confusing.
Do you have both iPhoto and Elements?

iPhoto '08 will import and export out .PSD files.
Or export out in jpg, tiff, png, etc.
(But if the .PSD file is 16-bit, it will be exported out as 8-bit.
Which may or may not be a concern to you.)

From iPhoto > File > Import to Library
you will see that iPhoto will allow you to add a .PSD file into iPhoto.
This will copy the .PSD file into the iPhoto database.

From iPhoto preferences Advanced, if "Copy items into the iPhoto Library"
is not selected, iPhoto will just point to the .PSD file.
I would gather then that any file that iPhoto modifies and exports is then
saved into the iPhoto database.

Most applications don't change photo file types unless you request the change during the saving process.

Some, like iPhoto, may change them on import, or necessitate that you change the file type, if the application can't import a file. Apps may not import certain file types for various reasons - especially if software is out-of-date.

This message has been edited. Last edited by: Chuck M,