C# - 如何更改 PNG 质量或颜色深度-C#/.NET问题

C# - How to change PNG quality or color depth(C# - 如何更改 PNG 质量或颜色深度)

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问题描述

我应该编写一个程序，从用户那里获取一些 PNG 图像，进行一些简单的编辑(如旋转)并将它们保存在 JAR 文件中，以便它可以将图像用作资源.问题是当我打开一个 80kb 的图像，然后用 C# 保存它时，我得到一个质量相同但空间为 130kb 的图像.而且因为它必须放在 J2ME jar 文件中，所以我真的需要更小的尺寸，至少是原始尺寸.我尝试了下面的代码，但后来发现它只适用于 Jpeg 图像.

I am supposed to write a program that gets some PNG images from the user, does some simple edits like rotation and saves them inside a JAR file so that it can use the images as resources. The problem is when I open, say an 80kb image and then save it with C#, I get an image with the same quality but for 130kb space. And because it has to go inside a J2ME jar file I really need lower sizes, at least the original size. I tried the code below but later found out that it only works for Jpeg images.

ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
                int j = 0;
                for (j = 0; j < codecs.Length; j++)
                {
                    if (codecs[j].MimeType == "image/png") break;
                }
                EncoderParameter ratio = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 10L);
                EncoderParameters CodecParams = new EncoderParameters(1);
                CodecParams.Param[0] = ratio;

                Image im;
                im = pictureBox1.Image;
                im.Save(address , codecs[j], CodecParams);

这是图片加载到图片框的地方:

This is where the image is loaded to a picture box:

private void pictureBox1_DoubleClick(object sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                string address = openFileDialog1.FileName;
                address.Replace("\", "\\");
                Image im = Image.FromFile(address);
                pictureBox1.Image = im;
            }
        }

这就是它在没有编辑的情况下被保存回来的地方:

And this is where it's being saved back with no edits:

private void generateToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (folderBrowserDialog1.ShowDialog() == DialogResult.OK)
            {

                ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
                int j = 0;
                for (j = 0; j < codecs.Length; j++)
                {
                    if (codecs[j].MimeType == "image/png") break;
                }
                EncoderParameter ratio = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 10L);
                EncoderParameters CodecParams = new EncoderParameters(1);
                CodecParams.Param[0] = ratio;

                string address = folderBrowserDialog1.SelectedPath;
                address = address + "\";
                address.Replace("\", "\\");

                Image im;
                im = pictureBox1.Image;               
                im.Save(address + imageFileNames[1], codecs[j], CodecParams);

注意:imageFileNames[] 只是一个字符串数组，其中包含一些必须用来保存图像的文件名.

Note: imageFileNames[] is just a string array that has some of the the file names to which the images must be saved with.

任何想法都将不胜感激并提前致谢.

Any ideas will be appreciated and thanks in advance.