generate bmp image with 300 dpi 24 bit in C# code

Saranya

I need BMP image with transparent backgorund to pass the image to Evolis card printer, but BMP cannot accept transparent background, so i found using PNG with transparent with (300 dpi and 24 bpp) convert to BMP via UWP APP

2 Replies

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Vijay Pratap Singh2y ago

Accepted answer

Here's a step-by-step guide to achieving this:

Create a PNG image with a transparent background using System.Drawing.
Save the PNG image.
Load the PNG image and convert it to a BMP image with the desired properties.
Save the BMP image.

using System.Drawing;
using System.Drawing.Imaging;

class Program
{
    static void Main(string[] args)
    {
        // Create a PNG image with transparent background
        Bitmap pngImage = new Bitmap(200, 200, PixelFormat.Format32bppArgb);
        using (Graphics graphics = Graphics.FromImage(pngImage))
        {
            graphics.Clear(Color.Transparent);
            // Draw something on the image if needed
            graphics.DrawString("Transparent PNG", new Font("Arial", 12), Brushes.Black, new PointF(10, 10));
        }

        // Save the PNG image
        pngImage.Save("transparent_image.png", ImageFormat.Png);

        // Load the PNG image
        using (Bitmap pngImageLoaded = new Bitmap("transparent_image.png"))
        {
            // Create a new BMP image with the desired properties
            Bitmap bmpImage = new Bitmap(pngImageLoaded.Width, pngImageLoaded.Height, PixelFormat.Format24bppRgb);
            bmpImage.SetResolution(300, 300); // Set DPI to 300

            // Draw the PNG image onto the BMP image to remove transparency
            using (Graphics graphics = Graphics.FromImage(bmpImage))
            {
                graphics.Clear(Color.White); // Set background to white
                graphics.DrawImage(pngImageLoaded, 0, 0);
            }

            // Save the BMP image
            bmpImage.Save("converted_image.bmp", ImageFormat.Bmp);
        }
    }
}

Hope this will help

Naimish Makwana2y ago

You want to create a BMP image from a PNG image with a transparent background, using a UWP app. Here is a sample code snippet in C# that uses the Windows.Graphics.Imaging namespace to convert a PNG image to a BMP image:

using System;
using System.IO;
using System.Threading.Tasks;
using Windows.Graphics.Imaging;
using Windows.Storage;
using Windows.Storage.Streams;

public async Task ConvertPngToBmpAsync(string inputFilePath, string outputFilePath)
{
    // Get the input file
    StorageFile inputFile = await StorageFile.GetFileFromPathAsync(inputFilePath);

    // Get a stream from the input file
    using (IRandomAccessStream inputFileStream = await inputFile.OpenAsync(FileAccessMode.Read))
    {
        // Decode the input file as a bitmap
        BitmapDecoder decoder = await BitmapDecoder.CreateAsync(inputFileStream);

        // Get the first frame of the bitmap
        BitmapFrame bitmapFrame = await decoder.GetFrameAsync(0);

        // Convert the bitmap to a SoftwareBitmap
        SoftwareBitmap softwareBitmap = await bitmapFrame.GetSoftwareBitmapAsync();

        // Get the output file
        StorageFile outputFile = await StorageFile.GetFileFromPathAsync(outputFilePath);

        // Get a stream from the output file
        using (IRandomAccessStream outputFileStream = await outputFile.OpenAsync(FileAccessMode.ReadWrite))
        {
            // Create a bitmap encoder
            BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.BmpEncoderId, outputFileStream);

            // Set the software bitmap
            encoder.SetSoftwareBitmap(softwareBitmap);

            // Set the DPI
            encoder.BitmapTransform.InterpolationMode = BitmapInterpolationMode.Linear;
            encoder.BitmapTransform.ScaledWidth = (uint)(softwareBitmap.PixelWidth * 300 / decoder.DpiX);
            encoder.BitmapTransform.ScaledHeight = (uint)(softwareBitmap.PixelHeight * 300 / decoder.DpiY);

            // Flush the data to the output file
            await encoder.FlushAsync();
        }
    }
}

This code reads a PNG image, decodes it into a SoftwareBitmap, and then encodes that SoftwareBitmap into a BMP image with a DPI of 300. The output BMP image is saved to the specified output file path.

Please note that BMP does not support transparency. If the input PNG image has transparent areas, they will be filled with black in the output BMP image. Also, please ensure that you have the necessary permissions to read and write files in the specified paths.

This code is for a UWP app, so it uses the Windows.Storage and Windows.Graphics.Imaging namespaces, which might not be available in other types of C# applications. If you’re not developing a UWP app, you might need to use a different approach.

Remember to call this method from an async method, or use Task.Run to run it from a synchronous method. For example:

Task.Run(() => ConvertPngToBmpAsync(inputFilePath, outputFilePath));

Please replace inputFilePath and outputFilePath with your actual file paths.

Thanks