Can someone explain pixels?

[joegaff]

Hi. I have recently upgraded from a 2 megapixel camera to a 5 megapixel. I now seem to take huge photos (like A4 size). There doesn't seem to be anyway to make them smaller apart from selecting 3 megapixels on the camera. What is the point of all the pixels if I have to resize them anyway? Why did I buy a 5 megapixel camera if I am inly going to use 3? I thought maybe the resolution would be greater not just the size. I am really confused.

Is a pixel a fixed size?

[irdreed]

joegaff,

Here's a site with a lot of information, Read the Digital Camera Buying Guide in five easy steps & that should explain the fundamental things:

http://www.digital-camera-buying-guide.com/

[joegaff]

Thank you. Looks like a great site.

[joegaff]

OK. Read all that and still a little confused. Seems like it's the resolution that is important not total pixels. Can you change the DPI on a digital camera? I can't seem to find a setting on mine that does this. I am using a Sony T1.

Thanks.

[buck52]

Originally posted by joegaff
OK. . Seems like it's the resolution that is important not total pixels. Can you change the DPI on a digital camera? I can't seem to find a setting on mine that does this. I am using a Sony T1.

Thanks.

Your camera probably has a fixed PPI that it takes pictures at...

Resolution is determined by Pixels per inch...PPI

The more total pixels your camera takes the better the resolution/quality of the end result...

If you want to produce a great 8x10 use all the pixels your camera will produce 5MP

If you only want a great 3x5 use the 3 MP setting...

the PPI wil be the same more or less...haven't got time to do the exact math but hopefully you get the idea

someone else will no doubt come along with a better explanation

buck

[irdreed]

joegaff,
The camera you have appears to be an excellent choice. You have 5 selections for taking pictures, according to the specs I saw.

It seems to me you are confusing what you see on your monitor versus what you can print out on paper. I would suggest reading information provided by Wayne Fulton here:
http://scantips.com/
I know this is referencing scanners but the principles that are explained are the same. Read especially the sections titled "Video Resolution", "Printing Resolution", and glance at any others sections that may help.

There are Photo Editing Programs that can change the size (in Pixels) if you want to view the object on a monitor. There are Photo Editing Programs that can change the size (in Inches) if you want to print that object.

So it seems to boil down to your individual choice as to the size you want to print or display.

Hope this helps.

[joegaff]

Thanks. Am reading it now.

[shiva_42]

All the advice so far is great... just a quick note...

For lack of a better analogy, pixels are the equivalent to "grains" in normal photographic emulsions. In other words, the pixels are actually the smallest practical element of your digital picture, just like the grains are the smallest practical element of a normal negative.

You can blow any picture up large, and eventually you will begin to see and distinguish the individual grains or pixels, which limits the practical size of the enlargement.

But, as previously stated, this is related to, but not the same thing as, the resolution being output to your printer.

The more pixels in your original pic, the higher the resolution, the larger the filesize, and the smaller the "grains" of the image, allowing maximum resolution and enlargement capabilities.

So, in conclusion, (hmmm, this wasn't such a short note afterall) the larger the image size, meaning the higher the number of pixels, is sort of equivalent to a larger negative to begin with (i.e. 4x5 compared to 35mm). And, other than storage requirements, you simply can't have too much resolution in the original image, because you can always size DOWN a picture without loss of resolution, but you can't create more pixels out of thin air to be able to enlarge a given picture past the practical limitations of it's original resolution. So shoot with the highest resolution, save the pics, then resize copies according to your distribution or printing needs...

Hope this helps?

[irdreed]

shiva_42,

Great explanation, simple but true with only one exception...

but you can't create more pixels out of thin air to be able to enlarge a given picture past the practical limitations of it's original resolution.

You can add Pixel .......it's called Interpolation.

[jerryctx]

Originally posted by irdreed
shiva_42,

Great explanation, simple but true with only one exception...


You can add Pixel .......it's called Interpolation.

Yes, but it doesn't add detail. It may make a "prettier" picture if you enlarge beyond the normal limit for the resolution.

[falcon2000]

In my experience, interpolation is only useful for the very mariginal files that need only a little nudge. Beyond that interpolation really won't help to give you a better image. In some cases it degrades the image as interpolation results in a more fuzzy picture.

[irdreed]

jerryctx, falcon2000,

Right on. I only tried to point out though that one "Could" add Pixels. In my experience I think I know how to get the final desired results I want. But it took a while to figure it out.

It seems to me that the human eye cannot tell if one does add small amounts of interpolation, such as scanning an object at 150 dpi and editing the object to say print a 200 dpi object. (Of course getting into Inkjet Printers is a whole new ballgame.) Also I'm not sure if all are aware that most printed photographs are only around 200 dpi.

So as I said, it was just to point out that a particular statement needed to have an additional viewpoint.

Thanks for the comments though.

[falcon2000]

Originally posted by irdreed
jerryctx, falcon2000,

Right on. I only tried to point out though that one "Could" add Pixels.

Oh, I knew that
My message is meant for joegaff coz' I don't want her/him to get the wrong idea.

[shiva_42]

Nah, I don't buy into that smoke-and-mirrors voodoo stuff like interpolation. Original sweeping generalization stands...

Of course, Genuine Fractals helps -- and I use it, but it's still not the same as more original pixels, know what I mean?