Constraints

Within each code I've introduced some constraints. They are more or less same for each code and are as follows:

i) Magnification Preference: You have the option to magnify
a) the plotted pixel only or
b) you can magnify the entire grid points alongwith the pixel

ii) Showing grids: If you opt not to magnify the grids there is no use of plotting it. In this case the grids will cover the entire screen(A nice food for thought).
When you magnify the grids you have an option to show the grid system. (variable name: show_grid)// default=1 shows the grid
However, the abscissa and ordinate will be showed throughout.(You can chalk out a strategy also to enable this option. Just a few more lines)

iii) Choosing Colors: For choosing colors you just have to change some values within the code. You can also take user input by just adding 'scanf's with the mentioned variable names:
a) You can choose the colors of the abscissa and the ordinate (variable name: axis_color) //default = 4;
b) Pixel Color: When you magnify the pixel the color of the plotted pixel (variable name: color) //default=14;
c) When a pixel is magnified, the basic pixel color(only the pixel point) can be chosen. It is also the color of the grids apart from the abscissa and ordinate. (variable name: basepix_col) //default=3;

One more thing to say, change the hardquoted "E://TC/BGI" directory to you own "TC//BGI" Directory. Best Wishes