increasing bitmap size without change in clarity

Its is absolutely positively and conclusively IMPOSSIBLE. You cant squeeze blood from a stone and you cant turn 40 into 800 without quality loss. You only have 1200 pixels to work with. You cant just magically turn it into 480,000.

weed

You forgot one:
"You cant make a silk purse from a sows ear"

 :-)  

baiju - weed is 100% correct.
To do this would be like making a 4 year old kids crayon drawing look like a photographic quality picture.

John

baiju,  a pixel is a set size and has essentially only one color in it. That color is the only information the pixel contains. 40 x 30 pixels contain just a finite amount of information. An image 800 x 600 contains many more pixels, and so it contains much more information about the image as a whole.  If you were to expend the 40 x 30 set of pixels, you would simply get more pixels, but no more information.

A typical camera picture contains the equivalent of about 2400 x 1600 pixel's worth of information. When you see a small physical sized picture, the "pixels" are very tiny - almost impossible to see", but if you "blow the image up" into a larger size you now can see all the pixels and so you now can see all the detail (information) contained in the full set of pixels.  But you cannot "blow up" a 40 x 30 pixel image into anything meaningful.  Understand ?

There is one software product by Altamira that is often used to create a larger image out of a smaller one. This uses a fractal mathematical algorithim to "interpolate" and create pixels of an appropriate color in spaces in the image in an effort to "fill in" the larger picture and make it look like the small one.  However, this kind of computer trickery works well only on fairly dense images (1240 x 780 and greater) that have a lot of pixels in the first place, and even then the resulting images only look good when they are about 25 - 30% greater than the original.  A starting point of only 40 x 30 pixels is too small for this kind of computer trickery to work with.

Does this explanation help?

Dear forester,
your expalanation is convincing. Thanks. Now i want to award you points. is it enough if i click accept comment as answer given against your name.

Hey, wait! I know how to do it!
but it has something to do with black magic..  ok maybe you should just give the points to forester ;-)

baiju, I totaly agree with the things said so far, but,
If you are looking for a way to resize the image and make the large image look as good as possible (smooth, reasonable) then there are methods like:
Billinear, Trillinear and Polynomial interpolation.
These methods create new information in the large image by "guessing" it from the behaviour of the pixels in the small image.
Let me know if you think it can help you.
Good Luck.

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