Digital picture quality.......??

Factual Questions
1

I take a picture at anywhere from 2 - 6 megapixels and crop out a section without changing the size, and it appears crisp and detailed when I upload to a webpage or to a friend.

If I resize at all, especially by about 50%, even saving at max, I seem to get a lot of degradation.

Right now I am using a Fuji F-10 and have tried several different picture handling programs.

Any suggestions of a camera or format or photo shop program that will give me the best quality in going from 2848 X 2136 X 24 to a 640 X 480 resize? Or is that impossible?

If I clip out a 640 X 480 from a larger pic, I get detail. If I resize, I lose a lot.

Do need to go to a camera that provides RAW info and a special photo shop program? Can it be done at all?

It would seem as long as I am going down and not up, that quality and detail would hold. --???

Or is it my monitor that can’t see the detail?

2

When you say “degredation”, what exactly are you referring to? Images that have been resized tend to lack crispness because a lot of information has been thrown away - a touch of sharpening should solve that problem. What software are you using? I recommend Picasa for basic image manipulation, and you can’t improve on the price. Picasa has a resize as well as a sharpen option, and it leaves your original pictures totally untouched, so even if you make some drastic changes, you haven’t lost anything. I’d give the sharpening thing a whirl and see if it makes any difference.

3

Do any of the following situations apply?

  1. When you resize a 2848x2136 image to 640x480 and then view it full-screen, it looks worse than the original. That’s to be expected because you’re throwing away information. This is the way it’s supposed to work. You can’t make an image smaller and still have it look as detailed – it’s the same way a wallet-sized picture will show less detail than a larger-than-life poster.

  2. When you resize a 2848x2136 image by 50% and save it, it looks worse than if you simply viewed the original at 50% zoom. If this is the case, the problem may be a matter of the resampling method used.

Which programs have you tried so far? Some use better resampling methods than others. Picasa is a great choice, as Dervorin suggested. Others include the free IrfanView and the shareware Paint Shop Pro.

  1. You’re saving the final image as a JPEG and it only looks bad after you save it. If this is the case, your program may be performing too much compression. If your prog lets you specify a JPEG compression level, try something like 15. (Some programs invert the compression percentage, so if 15 looks like absolute crap, try 85. You’ll know to do this if the image looks COMPLETELY wrong.)
4

I have those photo programs.

I am not trying to do anything full screen.

I guess I do not understand how they reduce the size of the picture.

Regardless of the resolution set on my monitor, the original picture, shot at .3 megapixel or 6.0 megapixel will look better in any one square inch than the same information in ½ square inch. I take two pictures the same except one is at .3meg and 640 X 480 and shows as 37k as stored untouched on my computer and the other is at 6.0 meg and 2848 X 2136 and shows as 2976K stored untouched in the file.

Now I open the pictures and the beach ball in each looks very sharp but very different in size. the 6.0 picture seems to have more detail and looks better over all but it is much bigger on the screen.

Now I take and cut out the beach ball in both shots and resample in the same program using everything the same, just a 50% reduction in size for each. the pictures are still not the same size because they started out different.

Now, to just look at them, the order of detail and sharpness and just plain quality is thus:
original 6.0
original .3
50% of 6.0
50% of .3

and if I make the images the same size which requires that I reduce the 6.0 picture to about 23%, then the original .3 meg picture is obviously the better picture although they are near the same size in stored information. (4K)

Since changing the size of the picture so reduces the quality, why use any amount of megapixels that causes the picture size to be bigger than a desktop view (800 X 600 ) if you are not going to print to a quality paper photo?

5

Okay,

Let me do it, and you tell me if you see the same thing.

This one, is at full 6 megapixel size:

Well, this picture:

Bodie Island Lighthouse is at full 6 megapixel size.

While this one:

(Bodie Island Lighthouse reduced) was reduced in Picasa2.

Are you seeing the same characteristic you see in your own work?

They look no different than I would expect them to, in terms of sharpness, considering the size.

Tris

“You can’t always get what you want.” ~ M. Jagger/K. Richards ~

6

[QUOTE=GusNSpot]
I have those photo programs.

I am not trying to do anything full screen.

I guess I do not understand how they reduce the size of the picture.

Regardless of the resolution set on my monitor, the original picture, shot at .3 megapixel or 6.0 megapixel will look better in any one square inch than the same information in ½ square inch. I take two pictures the same except one is at .3meg and 640 X 480 and shows as 37k as stored untouched on my computer and the other is at 6.0 meg and 2848 X 2136 and shows as 2976K stored untouched in the file.

Now I open the pictures and the beach ball in each looks very sharp but very different in size. the 6.0 picture seems to have more detail and looks better over all but it is much bigger on the screen.

Now I take and cut out the beach ball in both shots and resample in the same program using everything the same, just a 50% reduction in size for each. the pictures are still not the same size because they started out different.

Now, to just look at them, the order of detail and sharpness and just plain quality is thus:
original 6.0
original .3
50% of 6.0
50% of .3

and if I make the images the same size which requires that I reduce the 6.0 picture to about 23%, then the original .3 meg picture is obviously the better picture although they are near the same size in stored information. (4K)

[/quote]

If I understand you correctly, this is exactly the way it’s supposed to work. The smaller the image, the less detail you have. On a computer monitor, the more detailed image will appear “bigger” (in terms of dimensions) because the monitor has a fixed pixel density (DPI) (like 786K pixels in a 1024x768 monitor); if your image is higher resolution than that, your monitor can’t display the whole thing at once and thus you have to scroll around.

It’s different in print because you can print things at different DPIs while still maintaining the same physical dimensions. Monitor resolutions are usually around 72 DPI, while print goes up to the hundreds or thousands.

Well, the main reason IS printing.

But you might also want to crop out a certain section without losing information – for example, if you take a landscape photo at 6 megapixels, you’ll be able to crop out one of the small flowers in the foreground and have it be decently sized by itself. But if you took the original picture at 640x480, the cropped flower will look like shit because there wasn’t enough resolution there to capture it.

One last reason is that not every monitor is 800 x 600 – higher quality ones go up to 2000ish and beyond.

Oh, and can you post your images (use www.tinypic.com if you need a photohost) so we can see what you mean?

7

[QUOTE=GusNSpot]
…why use any amount of megapixels that causes the picture size to be bigger than a desktop view (800 X 600 ) if you are not going to print to a quality paper photo?
[/QUOTE]
This is a fair comment. If you have no intention of ever printing out a particular photo, but are only going to view it on your PC screen, then there is no point taking the photo in a higher resolution than your PC screen. You’re just wasting disk space.

If your 50% reduction of a 6.0 megapixel image ends up looking less detailed than a 0.3 megapixel original, then either your graphics program is using a truly awful resampling method, or your camera has a low-quality lens which is preventing it from taking advantage of the pixels available.

8

Some programs “resize” rather than “resample” images. Resizing loses a lot of information, whereas resampling keeps the image looking basically like the larger version, only smaller. As an example, if you had a white picket fence in the background of a large image, then resized it, some of the pickets might entirely disappear as the resize algorithm arbitrarily throws away information to make the image smaller. A resample algorithm trys to average out the colors in the large photo and still represent what was there. It won’t be as detailed or sharp as the large image, but should still like it to the eye.

Also, if you’re saving and re-saving the same JPG image, you’re going to get a progressively worse image every time as the data is lossily recompressed over and over.

9

[QUOTE=hammos1]
This is a fair comment. If you have no intention of ever printing out a particular photo, but are only going to view it on your PC screen, then there is no point taking the photo in a higher resolution than your PC screen. You’re just wasting disk space.

If your 50% reduction of a 6.0 megapixel image ends up looking less detailed than a 0.3 megapixel original, then either your graphics program is using a truly awful resampling method, or your camera has a low-quality lens which is preventing it from taking advantage of the pixels available.
[/QUOTE]

If the photos are the least bit valuable to you, don’t reduce them to save disk space. Photos are often irreplacable and disk space is getting cheaper all the time.

If you’re going to do anything, keep the original images untouched, and use a program like Thumbs Plus to batch-resample them to a smaller size.

10

Another quality trick is to reduce your photo in powers of 2 (50%, 25%, 12.5%, etc).

IIRC, jpg pictures are built on 4-pixel groups so reducing by 50% yields much better results than a 45% reduction. The math, and therefore the interpolation of pixels to a new size, is friendlier.

11

Thanks for the help. I am getting a better handle on it now.

The fixed DPI of the monitor is a major block as to what I want to have happen.

I do mostly save the originals as taken if they are any good. Space is cheap for now. Note my rename practice. I keep files of pics and reworked pics all in the same file for storage purposes.

12

Here are a couple of composit pictures I made of a test shot that gives you and example of what I am talking about.

Used two different cameras to help show the changes.

Used two different places to see about download speed.

http://users.wildblue.net/dragon/overall.jpg

13

Yup; as far as I can tell, everything’s working fine. You just can’t have as much detail in a smaller picture (in terms of pixel dimensions). There’s no real way around that.

But… what the hell IS that thing in your pics?

14

Total dia = about 1 inch. Seems to be a rubber and sparkly cat toy I think. Just something laying around that gave some small lines for detail observatiion.

15

[QUOTE=Triskadecamus]
Well, this picture:

Bodie Island Lighthouse is at full 6 megapixel size.

While this one:

(Bodie Island Lighthouse reduced) was reduced in Picasa2.

Are you seeing the same
[/QUOTE]

Your 6 megapixel picture looks worse to me. I get a good deal of aliasing (sort of a stair stepping up the side of the lighthouse) on the bigger picture. The smaller picture seems more crisp. Is that how it is supposed to work?

16

[QUOTE=Whack-a-Mole]
Your 6 megapixel picture looks worse to me. I get a good deal of aliasing (sort of a stair stepping up the side of the lighthouse) on the bigger picture. The smaller picture seems more crisp. Is that how it is supposed to work?
[/QUOTE]

Is your browser reducing the size of the 6 Meg image to fit on your screen? If so, that’s where the aliaising is coming from. In my browser the image is many times bigger than my desktop, and is crisp and clear.

17

[QUOTE=Telemark]
Is your browser reducing the size of the 6 Meg image to fit on your screen? If so, that’s where the aliaising is coming from.
[/QUOTE]

Whoops…yep. That was it.

18

[QUOTE=Whack-a-Mole]
Whoops…yep. That was it.
[/QUOTE]

Yeah that’s a browser feature that has probably caused untold confusion, people thinking images are crappy when it’s really just the browser doing a quick-and-dirty image resize instead of a resample.