Dodgy Camera Claims
Just a short one this, but Iv'e seen plenty of cheap cameras offered with ridiculous claims about their resolution (Megapixels.) etc.
First, you won't get a cheap digital with a genuine resolution of 8Mpix, it just doesn't happen. That sort of resolution belongs in the high-end of the market camera, or an SLR, and is very unlikely to cost less than £100. (That would be a bargain. I know prices are falling, but not that fast!)
So, if you see anything offered new with this kind of resolution, and it's cheap, then the resolution claim is probably fake. One way of lying about a cameras true capacity is to quote an 'interpolated' resolution.
Interpolated, and real resolution, the difference!
Interpolation, is a mathematical process of filling in the gaps between actual data points. Or to put it another way, guessing the stuff you don't actually have!
Interpolation just smooths over the pixels so you don't see them in the enlarged image, but it does not add more detail, which is why you would want lots of pixels in the camera in the first place!
If you want to know what interpolation looks like, you will find that most web-browsers will interpolate an image file to produce a 'smoother' image, simply because large images take a long time to download. In fact most picture viewers will interpolate as well, especially as you zoom in. (You usually need to view the picture using graphics manipulation software to see the actual pixels!) As the picture gets larger, the viewer needs to get the original pixels to fit the ones your display can actually show, and so needs to create new pixels to fill any gaps. This is best dome by interpolation.
So you will often find cheap cameras listed with high Mpix figures, but if you read carefully, it will (should) say 'interpolated' in the small print.
What's happening here is that the camera, (Or the software required to get the images into your computer.) applies a program to the low resolution image actually taken by the camera, padding it out with interpolated (Faked) pixels.
If you have never actually seen a high resolution image, you might be fooled into thinking that this is what you get from a high-res image. After all, your computer display will probably only (!) display about a million pixels, and unless you need to enlarge a part of the image you may not notice that there are fewer pixels than you paid for. You may however notice other effects associated with fewer pixels in the image, such as aliasing. (The moire effect you see when someone wears a striped suit on telly!)
Interpolation is not always bad, it can make a jagged scratchy image easier on the eye, so bear that in mind, but quoting an interpolated figure as the actual picture taking capability of the camera is just plain wrong!
You can always ask if the figure quoted is real or interpolated, and if it's interpolated, you need to know what the real resolution is. So if they won't tell you, what the real figure is (Or don't even know the difference between real and interpolated) then the seller probably wears a stetson, rides a horse, and carries a six-shooter:-)
Note: Sometimes you will see an 'effective' megapixel figure. That is not the same thing as interpolated, but a measure of how many megapixels in the cameras sensor are actually used. However, some may use it as a euphemism for 'interpolated'.
PS: there are a lot of Asian companies trying to palm these off to otherwise innocent eBayers. Iv'e been getting a lot of spam lately offering to supply me with large amounts of very cheap cameras with fake resolutions, by companies using faked-up user ID's. Iv'e reported them to eBay's Account Security team who are busy closing their faked accounts.
However, not every eBay seller is quite so scrupulous, (He says, polishing his halo!) and there is nothing stopping these 'companies' (Who knows who they are really!) from selling directly on eBay. So beware!