PHP image resize depending on height

Question

Hey all i am trying to figure out how to resize an image that has a higher height than width. The normal width and height of the area where the image needs to be displayed is:

width  = 1000px
height = 700px

What type of math would i need in order to resize that to the proper width/height above without screwing it?

The test image size is:

 width  = 1451
 height = 2200

I was thinking of doing this:

(700/org.height)

But that does not come up with the correct number of 462.

In photoshop, changing the height to 700 yields a width value of 462.

http://stackoverflow.com/questions/7863653/algorithm-to-resize-image-and-maintain-aspect-ratio-to-fit-iphone - it doesn't matter which language you apply this to. the math is the same. You know, though, imagemagick can do this very easily for you. — Kai Qing, Dec 14 '12 at 02:01
http://stackoverflow.com/questions/8674856/php-uploading-images-in-the-correct-dimensions My answer in this question should assist you with producing the dimension within the confines of a maximum size — Scuzzy, Dec 14 '12 at 02:07

score 1 · Accepted Answer · answered Dec 14 '12 at 02:15

so you want to scale your image so that it fits as large as possible within a 1000x700 square without stretching it? You could do something like this:

$availH = 700;
$availW = 1000;
$imageH = 2200;
$imageW = 1451;

// you know you want to limit the height to 700
$newH = $availH;

// figure out what the ratio was that you adjusted (will equal aprox 0.3181)
$ratio = $availH / $imageH;

// now that you have the $ratio you can apply that to the width (will equal 462)
$newW = round(imageW * $ratio);

Now you have $newW and $newH which are the new sizes for your image properly scaled. You could of course condense this down but I've written it out so each step is more clear.

That was it. Thanks, Jason! – StealthRT Dec 14 '12 at 03:08 — StealthRT, Dec 14 '12 at 03:08

score 0 · Answer 2 · answered Dec 14 '12 at 02:03

0

Formula to keep aspect ratio when resizing is

original height / original width x new width = new height

Source: http://andrew.hedges.name/experiments/aspect_ratio/

But you want to switch it around to the following I think:

original width / original height x new height = new width

answered Dec 14 '12 at 02:03

Rowan

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So for the height it would be 700 and then whatever that **original width / original height x new height** is for the width? – StealthRT Dec 14 '12 at 02:12
..That wont produce the **462** that photoshop does? – StealthRT Dec 14 '12 at 02:21

PHP image resize depending on height

2 Answers2