it's algebra at work :)
nicely done.
On Oct 15, 2004, at 8:57 AM, Gryffyn, Trevor wrote:
Good questions.. Here's some stuff to play with:
Heres my maths problems in 2 parts:
Problem 1) I need to scale down an image (eg: example.jpg) to height of 120 pixels while maintaining the images proportions.
eg: if i have an image of (height and width) 800x600 what would the dimensions be if the height was 120?
Proportions can be figured out by doing cross multiplication. Say you're trying to figure out percentages, do something like this:
x 75 ----- x ------- 100 185
Multiple cross ways and you get:
185x = 7500
Divide both sides by 185 to get just an "x = " and you get 40.54. 75 is 40.54% of 185.
You can use this to get your proportions for images too. It doesn't have to be 100 at the bottom of that one side. Say you have an image that's 1275 x 852 and you want to create a 120 x ???? Thumbnail.
1275 w 120 w ------ x ------- 852 h x h
1275x = 102240 (1275 times x = 120 times 852)
Divide both sides by 1275 and you get:
X = 80.19.... Which you might round to 80.
So a 1275 x 852 image scale down to 120 x 80.
Easy, right? :)
Problem 2) After getting the above image now I need the x and y parameters to cut a h120 x w90 thumb *from the center of the image*
eg: if from problem 1 the result is an image of 120 x 160 then x=35 and y=125 (I think, i told you i suck at maths.. :-D )
This one's even easier. Using the same 1275 x 852 image:
1275 w - 120 w = 1155 (difference in widths)
1155 / 2 = 577.5 (578 rounded let's say). That's how much space you'll have on either wide width-wise. That'll give you a 120w "center cut"
Do the same with the height:
852 - 90 = 762
762 / 2 = 381
So your top-left pixel to start cutting would be at 578 x 381.
Try it out and let us know how it worked.
-TG
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