Originally posted by Freedom_Dragon
Is it possible to find resolution of screen image in a video given the size of image? Say screen image is 0.5 MB in size, running at 30 fps for a minute.
Did you make this question up yourself? Because when you plug the numbers in, it won't give a clean answer.
Originally posted by skip to my lou
if you are looking for 2 variables (horizontal and vertical) then you need 2 equations to solve'em...but so far you have 1
skip to my lou is correct.
File size = bits per frame x frames per second x time in seconds
0.5MB (the figure you gave me)
0.5MB = half a megabyte (obviously)
1B = 8b (one byte equals 8 bits)
1000B = 8000b
1KB = 8kb (one kilobyte equals 8 kilobits)
1000KB = 8000kb
but 500KB = 4000kb
and 500KB = 0.5MB
.'. 0.5MB = 4000kb (kilobits), or 500KB (kilobytes)
Note that:
bits = resolution x bit depth
bytes = bits on 8
kilobytes = bytes on 1024
4000kb = bits per frame x 30 x 60
4000kb = bits per frame x 1800
bits per frame = 4000 / 1800
.'. the number of bits per frame =
The total number of bits per frame, is 4000/1800 as a fraction.
But you cannot calculate the individual horizontal and vertical components of the resolution (bit depth multiplied by the hoziontal axis of pixels and the vertical axis of pixels).
Unless you tell me one of the two, that is, the number of pixels across (horizontal),
or the number of pixels across (vertical axis)
I think that should work... but you won't see this type of question in IPT exam
It takes a few minutes to calculate without a calculator (!)
Originally posted by Freedom_Dragon
also wat is a colour depth?
I know wat a bit depth is
eg:- size of bitmap static image (still image)
Resolution*Color Depth{8 (256 colors)}
640x480*8
wat does the 8 mean
Colour depth, from my understanding is the number of possible colours or shades/tones.
This is the "other" number when comparing bit depths.
With a bit depth of 1, your colour depth (or range of possible shades, tones and/or colours) is 2.
Quoting your formula:
eg:- size of bitmap static image (still image)
Resolution*Color Depth{8 (256 colors)}
640x480*8
If you are calculating the filesize of a bit-mapped image, then that formula should read:
resolution* bit depth
The bit depth is the number of bits per pixel allowing for the range of 'colour depths' or possible colours.
So, using your example,
640*480*
8
Since you already know what the bit depth is, and allowing for 256 colours, you will know that:
A bit depth of 8, allows for 256 colours. (As you have said correctly in your post).
So the 8 signifies the bit depth, not the total range of possible colours (what I would assume to be the 'colour depth').
To remove confusion, I would rather call the 'colour depth' as the 'colour
range', or range of colours possible from the bit depth itself
Does that help you?
Multiply by 1, if it's 2 (black and white image)
x by 2, for 4 colours
x by 3, for grayscale (8 colours)
x by 4, for 16 (16 colours and greys)
x by 8, for 256 colours
x 16, for 65536
x 24, for 16777216 (true colour)
There are bit depths of 32 as well, but you do not need to know them for IPT
I suggest you stop at 8, as the examiners know how difficult it will be for 16-34, or even 32 bit depths
/edit
Taken from
Binary & ASCII Calculations
This is my advice, repeating what you had said in that particular thread:
Originally posted by Freedom_Dragon
I think they wont ask u to do any calculation like that.
I dont think u need to worry to much. (About calculations).
Cheers
