[Nowhere Matt]

I think I just forced myself to graduate from Kodak EasyShare software to Picasa 3.
I just downloaded it today and have only begun to explore.


EasyShare was reliable and very satisfying from the time of my first point and shoot digital up even with my K10 a few days ago but the program is nothing but errors now, perhaps trying to manage over 10,000 digital images. I have nearly 9 gb free space on the hard drive and do not have this much trouble with other programs on the c drive so my choice was to try some other basic photo editing and managing software on my new k drive.
I really like it so far and added new images but need to understand how it manages edits and saves previous images.

Somewhat excited Picasa plug for the day.

[Nowhere Matt]

Man I hope that they are right when they say, "there are no stupid questions..."

I have a quick question concerning FastStone Photo Resizer.
Can someone give me a brief explanation of it's process.
For instances when you take a single image file or group of files and resize and move that smaller file to a folder for example, is the remaining portion of the file kept in a temporary file folder and can presumably be swept away with disk clean up?
If a 2,000 kb file is reduced to 1,000 kb saving and sending it to a folder for future web posting, what has happened to that other 1,000 portion of the file?

[bc_the_path]

Matt, I believe simply there is no other half. The small version is -sort of- a summary of the larger one; so you should not expect another part...

[dosdan]

There are two ways to reduce the filesize of a photographic image:

1. Reduce the numbers of pixels in it. Photos in consumer cameras use 24-bit colour (8 bits/colour x the mixing of 3 primary colours = 24 bits/pixel = 3 bytes/pixel (1 byte=8 bits)).

Consider the size of a 1500pix wide x 1000pix high TIFF-format image file. Its size, without compression, is 1500 x 1000 x 3 = 4.5MB (simplifying here by using a megabyte of 1,000,0000 bytes.)

Now if we reduce its height & width by 50%, we decrease its uncompressed filesize to 25% of the original: 750 x 500 x 3 = 1.125MB.

2. Use either lossless or lossy compression. TIFF files can be losslessly compressed i.e. when the file is later uncompressed, no detail has been lost at all from the original image. However most natural images do not compress all that well losslessly as they are too random (mathematically speaking). Lossy compression, e.g. JPEG files, always throws away some of the info during compression, so the uncompressed version is not exactly the same as the original. However, it does this intelligently so, if used correctly, the average user will not notice the degradation.

JPEG compression can be very large e.g a 4.5MB image file may be compressed to 300KB. That's about 15% of its original size. There is usually a "Quality" option when saving JPGs. This varies the compression. It is non-linear, so 100% quality is not the same size as the original file (lossy compression always loses something), while, say 90% may be a number of times smaller than 100%. Using too much JPEG compression (too low a Quality value) makes a picture look blocky & indistinct.

If you are going to later work on a JPG file, reopen it, alter it and then resave it, this will further reduce the quality (compression is always lossy, so you're degrading the image each time you resave it). So if you planning to work on a image, it's better to initially save it as a large TIF (there is a option in TIF files to use lossless compression: "deflate" or "LZW") and only convert it to a JPG at the end.

There are other JPG stuff I haven't covered here, such as lossless rotation (no further loss), or the option of attempting to use the estimated quality (reduces the additional loss when resaving if little change has occurred).

Dan.

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Last edited by dosdan; 01-07-2009 at 04:59 PM.

[dosdan]

There is a 3rd way of reducing the filesize of an image: reduce its details. An image which has had a Median Blur filter applied will produce a smaller JPG, while a file which has had a Sharpen filter applied will result in a larger JPG.

Dan.

[dosdan]

Here some test sizes on a 1500x1000 TIFF file using "true" KB (1,024 bytes). Actual filesize is 4,508,248 bytes. The slightly greater size then the calculated 4,500,000 bytes is due to the overhead of the TIFF file header.

Code:

TIF             4,403KB  100%
TIF/LZW         3,120KB   71%
JPG 100%        1,190KB   27%
JPG  95%          617KB   14%
JPG  90%          435KB   10%
JPG  80%          297KB    7%
JPG  70%          237KB    5%

All JPGs used Progressive Encoding & Huffman Optimisation.

A difference is noticeable in the JPG from the TIF, in the graduation of sky colour, even at a Quality setting of 100%.

Test file is available here: http://users.on.net/~dosdan/test_image.tif

Normally, for JPG photos destined for viewing in this forum, I use a Quality setting of 92-100%.

Dan.

[dosdan]

As regards what happens to the original photo after you resize it & save it, it depends.

If you save the file to the same location. You can not have two files with the same name in the same location. So when you go to save your resized file, the program usually warns you "File exists. Do you wish to replace it" (unless you've disabled this overwriting warning in the options). If you answer "Yes" you will replace the original file with the smaller one. As far as you're concerned, the original is gone.

However you can choose to rename the resized file so you keep both e.g.

Original Photo.tif
Original Photo (resized).tif

Or you could save the resized version in a different location. For example in my case I often make a "Resized" folder off the folder where the original photos reside.

Some of these programs have an option to "Delete original". If that is enabled, then you will loose the original regardless of where you save the resized file or what you rename it.

[krs]

On the topic of Picasa 3, I am reasonably impressed. Navigation is intuative, editing can be fairly quick, auto redeye works fairly well. The couple times I have tried the "healing" tool came out with questionable results....

I also recently got Elements 7. Have not used as much yet...

[jezza323]

i use picasa quite a bit, especially handy if you use picasa webalbums to share your photos. very easy to select the ones you want, right click upload, choose a size and its done

[rparmar]

Can the damn thing read PEFs yet? This was an unfixed bug for at least a year. Then I gave up on it.

[Class A]

Can the damn thing read PEFs yet?

Yes, it can. It could in the one but last version already.

No tone curves, but Shadow, Fill Light, and Highlight correction work well most of the time. I only wish the stupid thing would set the control settings to where you left them so that you could also reduce not only increase later on (all the info necessary is there in the picasa.ini file).

Sharpening is still 100% or 0%. Nothing in between.

I like Picasa a lot as a browser, slideshow tool, photo uploader, and for limited PP (at least it doesn't touch the original!). But I'm considering to move to FastStone as a browser calling RawTherapee (also works on JPEGS!) from it.