What designing software needed to create a 2D image for Unity 3D?

Hi guys. I’m new in Unity3D and I want to develop a educational 2D game for my thesis. Is there a need of image editors like photoshop to create a character or a environment? thank you.

this is a nice free program for editing and creating images.

You can use Photoshop of course, or any other image editor, including MS Paint. Use whatever you are most familiar with.

Any Software that can flatten images such as PaintMS, or Paint.NET or best-of-all PhotoShop.

You do know that you can get 2D Images made inside of Blender, or 3DS Max/Maya. Simply make it and go into orthographic view and then take a picture or render from the angle you like. Orthographic is basic manipulating an image to 2D.