How Can I superpose an image and a graphics?

Question

I want to superpose an image with a graphics in order to evaluate their alignment.

I am writting this exemple of code.

s1 = Graphics[{RGBColor[{1,0,0}],Circle[{0, 1}]}];
model = ContourPlot[x^2 + y^2 - 1 == 0, {x, -2, 2}, {y, -2, 2}]
imref = Rasterize[s1, ImageSize -> {200, 150}](*suppose that is given by camera*)
Show[imref,model]; 
(*second method*)
immodel=Rasterize[model, ImageSize -> {200, 150}];
ImageCompose[imref,immodel]

I have an other idea, I can binarize the two images and Multiply them or do ImageDifference to get the result alignement but I need also to show graphically the results! Is there any idea to add the opacity or transparency parameters in order to see both images superposed images? thanks

Answer 1

Similar to inset or show you can also use Overlay. Related questions might be this. or this.

s1 = Graphics[{RGBColor[{1, 0, 0}], Circle[{0, 1}]}]
model = ContourPlot[x^2 + y^2 - 1 == 0, {x, -2, 2}, {y, -2, 2}]
img = Import["https://i.sstatic.net/3ynJe.png"]

Overlay[{img, s1, model}]

Answer 2

The trick to Inset..ing a raster is to supply the required offset/scale arguments:

   s1 = Graphics[{RGBColor[{1, 0, 0}], Circle[{1 - .05, .05}, 1]}, 
       PlotRange -> {{-2, 2}, {-2, 2}}];
   model = ContourPlot[(x - 1)^2 + y^2 - 1 == 0, {x, -2, 2}, {y, -2, 2}];
   imref = Rasterize[s1, ImageSize -> {400, 400}];
   Show[{Graphics[Inset[imref, {-2, -2}, {0, 0}, {4, 4}] ], model}, 
           PlotRange -> {{-3, 3}, {-3, 3}}]

This aligns the two circles (sorry I cant post graphics) by placing the "0,0" of the raster at the lower left of the range specified in the first graphics object, and scaling appropriately.

For some reason this looses the contour plot axes, but you can do within contourplot as a prolog:

ContourPlot[(x - 1)^2 + y^2 - 1 == 0, {x, -2, 2}, {y, -2, 2}, 
     Prolog -> Inset[imref, {-2, -2}, {0, 0}, {4, 4}],AspectRatio->Automatic]

Answer 3

You can try something like this I guess,

s1 = Graphics[{RGBColor[{1, 0, 0}], 
    Circle[{0, 0}, 1], {PointSize[.02], Point[{0, 0}]}}, 
   GridLines -> Automatic];
p1 = ContourPlot[x^2 + y^2 - 1 == 0, {x, -1, 1}, {y, -1, 1}, 
   GridLines -> Automatic, FrameStyle -> Directive[Orange, 12]];
ImageCompose[s1, {p1, 1}]

If Inset is used

Graphics[{{RGBColor[{1, 0, 0}], Circle[{0, 1}]}, 
  Inset[ContourPlot[x^2 + y^2 - 1 == 0, {x, -1, 1}, {y, -1, 1}, 
    Axes -> True]]}, Frame -> True, GridLines -> Automatic]