It sounds like what you're asking for is that mIRC be able to show inline images - either automatically when an image url is detected, or else a /command which can be used by a script after it detects an image url, then uses something like $urlget to download the image.
For inline images to work, there would need to be several config options added:
* Do you want to see animated gif's? (the answer is probably no)
* Where to store these images (probably an 'images' folder beneath where mirc.ini is located. Rather than creating a lot of subfolders so it can preserve filenames, there could be a way to have a 'fake name' that avoids collisions unless the image is a duplicate. Something like using the sha1 hash of the image as the filename, which would simplify checking that avoids cluttering your images folder with multiple copies of the exactly identical image. Then there could be an images.ini where each item is the SHA1 hash of the file, and the data indicates the channel it was displayed in, as well as the url from which it was downloaded, etc. If images.ini also contained another section where each item is $sha1(url) that can cut down on wasted effort when someone posts a url whose image you already have in your folder - unless that kind of shortcut is undesirable for some kind of image url's where the image at a fixed url is possible to change.
* How many megabytes you want in the image folder before it starts deleting things to make room. Maybe the default would be the lesser of X megabytes or Y percent of free disk space
* A blacklist of sites that you do NOT want to see
* A whitelist of sites that needs to be on the list before the image will be seen
* A blacklist of #channels where you don't want to see any images
* A whitelist of #channels that needs to be on the list before the image will be seen
* How tall can the box be for imagines to be displayed inside
Some of the whitelist/blacklist settings could also be handled in some kind of ON IMAGE event which can be halted by a script, such as if there are some channels where it doesn't want to see any images unless they're a url from an @op/+voice or someone on some kind of whitelist
Perhaps an alternate setting for inline images is for people who don't want to see an image unless they right-click on an image url and choose the option to fetch the image