I've read around
that using imageMagick, I can make a high res image similar to Flickr. Even when using the highest quality and imagecreatetruecolor, JPGs are slightly blurry. This is most noticeable when the image contains text. The solution using imageMagick is using some -resize-recursive function. I'm pretty sure imageMagick just uses the PHP GD libary, so how does it use the GD to correctly display an image?
highest image quality
You can use the optional 3rd parameter to imagejpeg() to specify the desired quality (with 100 being the best). Or you could even use imagepng() (which also has an optional quality parameter) which may give you even higher resolution, since PNG is generally not as highly compressed as JPEG.
At 9 for PNG and 100 for JPG it still shows some blur.
In ImageMagick, are you using: Set(quality=>100) for your jpg? I think that insures zero compression.
I am not using ImageMagick, but since I know that it's only using PHP, I was wondering how to accomplish the same thing with good old GD
In some cases ImageMagick has created better thumbs for me. Resizing an image containing text is really a bugger. You might have to accept "some blur" as good enough.