CODEWITHSUNDEEP
phpimageresizeaspect-ratio
Orangeman555
Orangeman555

Reputation: 1181

Image Resize Math, but not Resizing Itself

Is there a php function which will do image resizing math itself but not create a new file?

I created a simple proportionally-resize-an-image math script and I realized there is more to it than just geometry, such as aspect ratio and such. Basic geometry math squashes the image a little.

If anyone is curious, it's simply to give the user a preview of image dimensions should they choose to download, but I'd rather not clutter up the server with tons of size variations of similar images :D.

Thanks.

edit: Per request, here is the key part of the resizing code: 

$ratio = min( $resize_to / $width, $resize_to/ $height );   

$width  = $ratio * $width; 

$height = $ratio * $height;

When I see the values output, I simply do a resize in photoshop using the values and the photoshop version squashes (I do this as a visual test), so I assume my code is faulty.

Upvotes: 0

Views: 569

Answers (2)

Orangeman555
Orangeman555

Reputation: 1181

This is funny. I was resizing one file, then checking another in photoshop. Human error. Went around the block to cross the street and had already crossed the street without knowing it..

Upvotes: 0

regulatethis
regulatethis

Reputation: 2352

The math required to scale an image while respecting aspect ratio is pretty straightforward. Some pseudo code:

original_width = <width of image before resizing>
original_height = <height of image before resizing>

new_width = <the max width desired for the resized image>
new_height = <the max height desired for the resized image>

if original_width >= original_height
  ratio = original_width / original_height
  new_height = new_width / ratio
else 
  ratio = original_height / original_width
  new_width = original_height / ratio
end

print "Width: " + new_width
print "Height: " + new_height

The above can probably be significantly improved but I just meant to illustrate the point.

Upvotes: 3

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