Take part of the image by coordinates

Question

I have four coordinates in the image, and I am interested in taking this polygon from the image. I try to do it in the following manner:

Edit: I use the solution from the @kglr answer, unfortunately, it does not take the correct part of the image. The link to the image is: https://www.dropbox.com/s/w58sikz2jip2sbg/19725.tiff?dl=0

coords = {{1983.44`, 992.097`}, {2034.18`, 1009.01`}, {2027.91`, 
    1027.18`}, {1977.8`, 1009.01`}, {1983.44`, 992.097`}};

polygon = Graphics[{
    EdgeForm[{Thick, Black}],
    FaceForm[], Polygon@coords
    },
   ImagePadding -> 0,
   PlotRangePadding -> 0,
   ImageMargins -> 0
   ];
mask = Graphics[
   Polygon@coords,
   ImageSize -> ImageDimensions[img],
   AspectRatio -> Automatic
   ];

Answer 1

You can use ImageAdd using the polygon as mask:

image = Import["ExampleData/spikey.tiff"]

SeedRandom[1]
coords = Transpose[{RandomReal[ImageDimensions[image][[1]], 4], 
    RandomReal[ImageDimensions[image][[2]], 4]}];
coords = coords[[FindCurvePath[coords][[1]]]];
polygon = Graphics[{EdgeForm[{Thick, Black}], FaceForm[], Polygon@coords}, 
   PlotRange -> Thread[{0, ImageDimensions[image]}]];
mask = Graphics[Polygon@coords, 
   PlotRange -> Thread[{0, ImageDimensions[image]}]];

Show[image, polygon]

ImageAdd[image, mask]

For image2 from the updated version of the question:

coords2 = {1977.8, 1009.01, 1983.44, 992.097, 2034.18, 1009.01, 2027.91, 1027.18};
coords2 = Partition[coords2, 2];
mask2 = Graphics[Polygon@coords2, PlotRange -> Thread[{0, ImageDimensions[image2]}]];

Show[image2, Graphics[{Red, mask2[[1]]}]]

ImageAdd[image2, mask2]

ImageTake[ImageAdd[image2, mask2], 1363 - { 1035, 975}, {1945, 2048}]

Answer 2

HighlightImage and ImageTrim can deal with polygons directly. That can be used to extract polygons from images:

polygon = Polygon[{{1132., 621.4}, {1153., 951.1}, {1490., 919.1}, {1555., 583.6}}];
highlighted = HighlightImage[img, {EdgeForm[], polygon}, "Remove"]

ImageTrim[highlighted, polygon]

If we didn't have HighlightImage and ImageTrim then I would do it like this:

{dimx, dimy} = ImageDimensions[img];
mask = Rasterize@Graphics[{White, polygon},
    Background -> Black,
    PlotRange -> {{0, dimx}, {0, dimy}},
    ImageSize -> {dimx, dimy}
    ];
ImageCrop[mask img + ColorNegate[mask]]

(One can also use addition instead of multiplication, as in kglr's answer, with ImageCrop.)

Answer 3

You can use Texture[]

img00=ExampleData[{"TestImage", "Lena"}] //ImageTake[#,200]& //Show[#,Frame-> True]&  

pts00={{10,50},{250,10},{150,200},{50,150}};
pts00Scaled=(#/ImageDimensions[img00])& /@ N[pts00];  

Graphics[
      {
         Texture[img00 ],
         Polygon[pts00,VertexTextureCoordinates-> pts00Scaled],
      },
   ImageSize-> 500,Frame-> True,
   PlotRange-> {{0,512},{0,200}}
  ]  

here is a advanced use of Texture[] on Polygon[].