by Rich Bloechl

A simple way to enlarge a drawing or picture is to use the GRID method. With this method, you simply draw a grid over your original sketch or print and then proportionately, draw a larger grid onto your painting material. Then you draw and copy as much detail as necessary from the originals grid to your larger painting grid.

A proportional scale wheel makes it easy to figure out the enlargement grid size, but it can be figured out mathematically also. A proportional scale can be obtained from most office or art supply stores. Here is how the grid system works by example to transfer the image of a watercolor painting.

First, a paper print of a photoshop generated composition was made. Cropping can be done on the original print, indicated by the heavy black outline on figure 1. This area measures 3 inches by 4-1/2 inches. The final painting will be approximately 12 by 18 inches. This proportion turns out to be an even 400%.

The size of the grid on the original depends on how detailed the image is and how accomplished you are at drawing; for this image, a 1/2-inch grid would work. So next a 1/2-inch grid pattern was penciled onto the paper print as shown to the left. Sizing the next grid is calculated by using the proportional percentage of 400%. 1/2 inch times 400% equals 2 inches. Thus, a 2-inch grid is penciled on the 12″ by 18″ watercolor paper area.

Once the larger grid is completed, then pencil in the outlines of the basic shapes of the subject, referring to the small print grid and transferring those lines or shapes to the appropriate grid of the larger watercolor paper. Draw as much detail as needed. When you are done, you should have a perfectly proportional enlargement of your original image as seen below.

If you don’t have a proportional scale, an engineering method can be used to create the larger grid points. You will need a straight edge and a triangle to do this. Once the grid has been established on the original piece, these points can be used to create the larger proportional grid points.

On the edge of the painting surface or another piece of paper, draw a line the length of the original and mark the grid points on that line (A).

Then draw a line that represents the length of the enlarged painting, at a slight angle away from the first line, that intersects that line at one end. Now draw a line from the end of the first line (A) to the end of the second line (B).

The angle that this line creates, will establish the proportional grid points on the longer line. By using the straight edge and the triangle to maintain the angle established, move the triangle along line A and draw a connecting line across to line B. Where the lines intersect establishes the larger grid points. Transfer this measurement to the final painting surface to create the proportional grid as shown in the final image below.

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"Contemplation : A Demo"