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Editorial Team
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Asked: 2026-06-10T13:00:01+00:00

using (var mem = new MemoryStream()) using (var bmp = new Bitmap(85, 54)) using

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using (var mem = new MemoryStream())
using (var bmp = new Bitmap(85, 54))
using (var gfx = Graphics.FromImage((Image)bmp))
{
    // gfx.SmoothingMode = SmoothingMode.AntiAlias;
    gfx.PageUnit = GraphicsUnit.Millimeter;
    gfx.FillRectangle(Brushes.Red, new Rectangle(0, 0, bmp.Width, bmp.Height));

    //add question
    gfx.DrawString(captcha, new Font("Arial", 5), Brushes.Blue, bmp.Width / 2, bmp.Height/2);

    //render as Jpeg
    bmp.Save(mem, System.Drawing.Imaging.ImageFormat.Jpeg);
    img = this.File(mem.GetBuffer(), "image/Jpeg");
}

return img;

this not work.
I need 85×54 millimeter

how do this?

I need draw for print

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1 Answer

  1. Editorial Team

    The size of this Bitmap is in pixels.

    When you display a bitmap on a regular display a single pixel will be 1/96th of an inch. Other displays might have other DPI’s (Dots Per Inch) – such as Retina displays

    Most printers support at least 300 DPI.

    So what you need to do is get the DPI of the screen or printer and size the bitmap accordingly or use a image format (vector?) that allows you to specify the DPI. Some bitmap formats also allow you to specify the intended DPI

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