Coldfusion resize making image files bigger?

Question

So I have an image loader that before it uploads the file to Amazon S3 it optimises the image by using this code:

<cfset ImageScaleToFit(myImage,1260,"")>
<cfset imageWrite(myimage,"newImagelocation", 0.9)>

The odd thing is that if I upload an image that is already 1260 wide and 24k in size, then optimise it using the above code, the image becomes 34k in size.

Why would optimizing an image make it bigger?

Answer 1

ColdFusion function ImageScaleToFit() does not do optimization. It just converts the width/height according to arguments. When doing this the algorithm for interpolation is highestQuality by default. Which could sometime increase the size of the file due to underlying mechanism. Even though you are using the 0.9 for quality when you write that only reduces a little bit from the initially pumped up size in ImageScaleToFit() call.

If you wish to reduce the size, then specify any other algorithm which is less costlier than highestQuality.

eg. mediumQuality, highestPerformance etc.