Question

我有一个MVC应用程序，您可以上传图片并将其调整为最大值。 50KB。我在while循环中调整大小，但问题是当我减小文件大小增加的图片的宽度和高度时。在某一点上，尺寸变小但是以质量为代价

.content{
  width:80%;
  height:300px;
  margin:10px auto;
  background-color:gold;
  text-align:center;
}

要调整大小的代码：

    Request.InputStream.Position = 0;
    string Data = new System.IO.StreamReader(Request.InputStream).ReadToEnd();
    var Base64 = Data.Split(',')[1];
    var BitmapBytes = Convert.FromBase64String(Base64);
    var Bmp = new Bitmap(new MemoryStream(BitmapBytes));

    while (BitmapBytes.Length > 51200)
    {
        int Schritte = 20; //I tested here also with 300
        int maxWidth = Bmp.Width;
        maxWidth = maxWidth - Schritte;
        int maxHeight = Bmp.Height;
        maxHeight = maxHeight - Schritte;
        Bmp = ScaleImage(Bmp, maxWidth, maxHeight);
        var base64 = ReturnImageAsBase64(Bmp);
        BitmapBytes = Convert.FromBase64String(base64);
    }

我从66964字节的大小开始。在循环中第一次转弯之后它的85151字节，这虽然宽度减少了300像素，高度减少了420像素。

Answer 1

从我之前的评论：

我想说这是你的Pixelformat问题。如果您有一个带有1bpp（黑色或白色）的Bitmap并将其绘制到ScaleImage中的newImage，则使用默认的Pixelformat创建newImage，这可能与Colors一起使用，因此最终得到24bpp，这会导致更高的内存大小

尝试更改：

import Tkinter as tk
import Queue

class MainWindow(tk.Frame):
    """ This is the GUI
        It starts threads and updates the GUI
        this is needed as tkinter GUI updates inside the Main Thread
    """
    def __init__(self, *args, **kwargs):
        # Here some initial action takes place
        # ...
        self.queue = Queue()
        self.start_threads()
        self.__running = True
        self.update_gui()

    def start_threads(self):
        """ Here we start the threads
            for ease of reading only one right now
            thread_handler_class is a class performing
            tasks and appending results to a queue
        """
        thread = thread_handler_class(self.queue)

    def update_gui(self):
        """ Update the UI with Information from the queue """
        if not self.queue.empty():
             # we need to check for emptiness first
             # otherwise we get exceptions if empty
             while self.queue.qsize() > 0:
                 # handle the data
                 # self.queue.get() automatically reduces 
                 # qsize return value next round so if no 
                 # new elements are added to the queue, 
                 # it will go to zero
                 data = self.queue.get()
                 # do stuff here
                 # ...

        # Set up the cyclic task
        if self.__running:
            self.after(100, self.update_gui)
            # if neccessary we can also restart the threads
            # if they have a determined runtime
            # self.after(100, self.start_threads)        

if __name__ == "__main__":
    APP = MainWindow()
    APP.mainloop()

到

Bitmap newImage = new Bitmap(newWidth, newHeight);

编辑：由于使用索引的PixelFormats似乎无法从中创建图形对象，因此似乎没有简单的解决方案。

解释图像尺寸较大的原因：

原始图片：颜色查找表：

Bitmap newImage = new Bitmap(newWidth, newHeight, image.PixelFormat);

这里有16个像素，16个像素，12个字节用于查找表（索引号为1个字节，每个颜色为RGB通道为3个字节）因此，图像的总大小为28字节

在newImage中没有查找表，因此每个Pixel都有完整的RGB信息：

1 = Red   = 255,  0,0
2 = Black =   0,  0,0
3 = Green =   0,255,0
...

         Column    
    Row  1  2  3  4
      1  1  1  1  1
      2  1  1  1  1
      3  2  2  2  2
      4  3  3  3  3

因此newImage的大小为3 * 16 = 48 Bytes

C＃ - 降低图像分辨率会增加文件大小

1 个答案: