I didn't know this one off the top of my head. If you use steemitimages to host the image, you can add a https://steemitimages.com/{height}x{width} to the start of the url.
To make this sequence of images:
<div>
https://steemitimages.com/0x0/https://steemitimages.com/DQmZBhZLPhqKiHZmLW2tFupUXCtM9dPP4mh85DtLGSwxrrm/171005_Masterpost_Icons-01.png
https://steemitimages.com/100x100/https://steemitimages.com/DQmZBhZLPhqKiHZmLW2tFupUXCtM9dPP4mh85DtLGSwxrrm/171005_Masterpost_Icons-01.png
https://steemitimages.com/50x50/https://steemitimages.com/DQmZBhZLPhqKiHZmLW2tFupUXCtM9dPP4mh85DtLGSwxrrm/171005_Masterpost_Icons-01.png
</div>
Fantastic!!!! Thank you.
the best contribution with which I could come across. Many thanks!!
tsss markdown sorcery!
Whoa! That's a great trick!
This is great - I've always wondered how to do this and now I know! Thank you