I'm looking for a free downloadable software to turn 2d image into 3d. I've seen a couple of free applications online which do that, but I'm looking for a software I can install in my computer. Is there any?
If you are considering as your source of the 2D image, a simple (or possibly slightly complex) vector image (line drawing), it is also important to present the form of the 3D model created.
There are a number of 3D modeling packages that are free and multi-platform, which allow one to import the 2D image, typically in SVG or similar vector format. It can then be extruded to a desired thickness within the program.
OpenSCAD is free and will import and extrude. It's a bit obscure but a powerful program. I like to use Inkscape to manage the vector image, then use an Inkscape extension known as Path to OpenSCAD.
Tinkercad is an online program that will import a flat vector image and allow extrusion, followed by exporting as an STL file.
Other software such as OnShape and Fusion360 provide similar options, with an increased number of export types as well. These two are a bit more complex but easily handled with YouTube tutorials.
If your objective is not to extrude a shape, this should be clarified by editing the question.
The only other consideration I can think of is that you are suggesting photogrammetry, but that requires multiple images of the same object taken from different locations around the object.
If by "3-d" you mean a steroscopic image (use red/blue glasses to view) you can use ImageMagick to do it -
montage -geometry 1200x1600 10 10 -background black -bordercolor black leftimage.jpg rightimage.jpg stereoscopicimage.jpg
composite left.jpg right.jpg -stereo 0 3d.jpg
I've done similar using the same tools, starting wtih a single flat image. Open it in the Gimp, shove it 10 pixels left and export as left file, shove it 20 pixels right (back to center, then 10 more right) and export as right side file. Then merge. Hardest part was picking a good source file... this is on my personal server so I don't want to embed or direct link - gruv dot org slash 3d356.jpg