Answer:
PNG
Step-by-step explanation:
Convertible or not :
First of all you should know that you can't make a JPEG image transparent. You should use a format that allows transparency, like GIF or PNG TIFF.
PNG VS GIF VS TIFF :
When we talk about which one to use there are two things that comes in mind.
1. Flexibility :
JPG has Millions of colors to use. it is used for Still Images Photography
GIF has Maximum 256 colors and is used for Simple animations
, Graphics with flat colors Graphics without gradients
PNG-8 has Maximum 256 colors used for Similar to GIF with Better transparency but no animation and known Great for icons
PNG-24 has Unlimited colors Similar to PNG-8 Handles still images and transparency
SVG has Vector with Unlimited colors Graphics/logos for web
Retina/high-dpi screens
2. Size
Size depends on the colors you will use.