I tried looking around but couldn't find plugin for this. I do not want to add new custom image size, that part I understand well, and this is not regarding featured image or post thumbnail.
What I want is, regular post image thumbnail in post, which shows in excerpt if it falls in beginning, to be replaced with different image size when showing on home, or category page.
I have regular thumbnail of 150 x 150 , but when viewed on index, I want it to be displayed in custom size of 150 x 90 (I have already added custom image size in functions.php.
Is this possible?