Saving graphics object in order to manipulate it later?

Question

I've generated a bunch of graphics using ContourPlot wich, given the nature of my problem, take a long time to create, and I was wondering if there is a way to save the object (not the image) to a file so I can retrive it later to manipulate, i.e. use Show, change colors, add text, etc.

For example, suppose I define something like

conic = ContourPlot[x^2/9 + y^2/16, {x, -10, 10}, {y, -10, 10}, 
    ContourStyle -> Red, ContourShading -> None, Contours -> 15, 
    Axes -> True, AxesLabel -> {x, y}]

then by doing

Definition[conic]

I can see the objetc:

Now, what I'd like to do is save the object in such way that I'll be able to change the color from red to blue, the labels, the aspect ratio, etc. by just importing it and modifying the proper options without having to calculate it again.

I guess a rudimentary solution would be to export the object to a txt file, and later import it, manipulate it and then use ToExpression, but I was wonderign if there is a more "within" approach.

I hope this isn't a duplicate. I've tried to search for the answer but the keywords save and graphics made it impossible.

Answer 1

You could use Put and Get:

conic = ContourPlot[x^2/9 + y^2/16, {x, -10, 10}, {y, -10, 10}, 
  ContourStyle -> Red, ContourShading -> None, Contours -> 15, 
  Axes -> True, AxesLabel -> {x, y}]

conic >> "conicfile";

(* later... *)

con = << "conicfile";

con /. Red -> Blue

Answer 2

As far as I know, they're never images in the first place unless you explicitly Rasterize them. When you load the notebook, Mathematica is building it up from the FullForm structure. Open up a Mathematica notebook in Notepad and you'll see that it's just a bunch of Mathematica structure, no images. So Mathematica already does what you expect.

If the object is very large though, one option is Export["c:/myfile.mx", conic] which saves it in a raw Mathematica binary format that you can later read in with conic = Import["c:/myfile.mx"]. I'm not sure this is strictly advantageous, though. Mostly it will help load the object faster.