Jan 27th, 2016 at 01:08 PM

How to Resize Image Dynamically in PHP

Today almost every website you visit show content in form of thumbnails. Thumbnails are nothing but images displayed next to the content. Be it News website or a blog, displaying images next to content is key to appeal user. Even our blog shows images as thumbnails on home page. A prerequisites to show Thumbnail in a webpage is that thumbnail must be small enough. So that many thumbnails can be loaded as fast as possible. Hence almost every website resize the image to create small thumbnails. So how to do this on the fly? How to resize an Image dynamically in PHP? There is an extremely useful PHP library called timthumb which comes very handy. It’s just a simple PHP script that you need to download and put in some folder under your website. And then simply call it with appropriate arguments. 1 Download timthumb.php and put under any folder. 2 Upload this script timthumb.php though FTP to your web hosting. Put it under a directory /script. 3 Just call timthumb.php with appropriate arguments, For example:

<img src="/script/timthumb.php?src=/some/path/myimage.png&w=100&h=80" alt="resized image" />

And that’s all!! One thing worth noting here is that this library will create a folder cache in the directory where timthumb.php script resides. This folder will cache the resized image for better performance. You can refer following table for different parameters and its meaning.

&nbsp	Parameter	Values	Meaning
src	source	url to image	Tells TimThumb which image to resize
w	width	the width to resize to	Remove the width to scale proportionally (will then need the height)
h	height	the height to resize to	Remove the height to scale proportionally (will then need the width)
q	quality	0 – 100	Compression quality. The higher the number the nicer the image will look. I wouldn’t recommend going any higher than about 95 else the image will get too large
a	alignment	c, t, l, r, b, tl, tr, bl, br	Crop alignment. c = center, t = top, b = bottom, r = right, l = left. The positions can be joined to create diagonal positions
zc	zoom / crop	0, 1, 2, 3	Change the cropping and scaling settings
f	filters	too many to mention	Let’s you apply image filters to change the resized picture. For instance you can change brightness/ contrast or even blur the image
s	sharpen		Apply a sharpen filter to the image, makes scaled down images look a little crisper
cc	canvas colour	hexadecimal colour value (#ffffff)	Change background colour. Most used when changing the zoom and crop settings, which in turn can add borders to the image.
ct	canvas transparency	true (1)	Use transparency and ignore background colour

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