当前位置：网站首页>Character painting, I use characters to draw a Bing Dwen Dwen

Character painting, I use characters to draw a Bing Dwen Dwen

2022-07-05 02:21:00 【Procedural ape Aaron】

Articles are constantly updated , You can pay attention to the official account. Program ape Alan Or visit Unread code blog .
this paper Github.com/niumoo/JavaNotes Included , welcome Star.

hello , Hello, everyone , I'm Alan .

already 2022 Years. , The mascot of the recent Beijing Winter Olympics Ice mound A fire , It is said that one pier is hard to find , All kinds of video news are overwhelmed . Programmers should have a programmer's way , Today I'll use Java Draw a Bing dwen dwen made of characters to everyone. , This article records the idea and process of generating character patterns .

Here is a character [email protected]#&8*0. Characters of ice block pier pattern .

1. Character pattern idea

We all know that a digital picture is a two-dimensional image , It uses a The limited two-dimensional array holds the color information of each pixel , The color information of these pixels is usually used RGB Mode to record . So in essence , Our common image is a two-dimensional array that holds pixel information .

Based on the above picture principle , We can find out , If you want to convert a picture into a character pattern , It only needs Convert the color information of each pixel into a character That's all right. , So we can figure out the steps to convert the picture into character pattern as follows .

Zoom the picture to the specified size , In order to ensure that the number of characters output will not be too large .
Traverse the pixels of the picture , Get the color information of each pixel .
According to the color information of pixels , convert to grayscale （ brightness ） Information .
Convert the brightness information into corresponding characters .
Output character pattern , That is, print a two-dimensional character array .

2. Zoom in and out of the picture

As mentioned above , Since we want to convert the color information of each pixel into a character , If there are too many pixels , Although it will increase the reduction of character images , But it looks very troublesome , Because of so many characters, your screen may not be finished .

therefore , We need to zoom the picture first , Zoom to a certain size and then character it . This is just for convenience , Use it directly Java The self-contained image processing method is used to zoom the image , The following code examples all specify the width for scaling , The height is scaled after being calculated in equal proportion .

Java There are two main ways to adjust the size of the picture. ：

Use java.awt.Graphics2D Resize the picture .
Use Image.getScaledInstance Resize the picture .

2.1. java.awt.Graphics2D

Graphics2D yes Java The platform provides the ability to render 2D shapes 、 Text 、 Basic class of image , Here's how to use Graphics2D Simple example of image resizing .

/**
 *  Picture zoom 
 *
 * @param srcImagePath   Picture path 
 * @param targetWidth    Target width 
 * @return
 * @throws IOException
 */
public static BufferedImage resizeImage(String srcImagePath, int targetWidth) throws IOException {
    Image srcImage = ImageIO.read(new File(srcImagePath));
    int targetHeight = getTargetHeight(targetWidth, srcImage);
    BufferedImage resizedImage = new BufferedImage(targetWidth, targetHeight, BufferedImage.TYPE_INT_RGB);
    Graphics2D graphics2D = resizedImage.createGraphics();
    graphics2D.drawImage(srcImage, 0, 0, targetWidth, targetHeight, null);
    graphics2D.dispose();
    return resizedImage;
}

/**
 *  According to the specified width , Calculate the proportional height 
 *
 * @param targetWidth    Target width 
 * @param srcImage       Image information 
 * @return
 */
private static int getTargetHeight(int targetWidth, Image srcImage) {
    int targetHeight = srcImage.getHeight(null);
    if (targetWidth < srcImage.getWidth(null)) {
        targetHeight = Math.round((float)targetHeight / ((float)srcImage.getWidth(null) / (float)targetWidth));
    }
    return targetHeight;
}

In code BufferedImage.TYPE_INT_RGB Represents the color model used , All color models can be in Java doc - Image See... In the document .

Resized pictures can be saved in the following ways .

BufferedImage image = resizeImage("/Users/darcy/Downloads/bingdundun.jpeg", 200);
File file = new File("/Users/darcy/Downloads/bingdundun_resize.jpg");
ImageIO.write(image, "jpg", file);

Now the original picture is 416 x 500 Image of the Bing dwen dwen to zoom in to 200 x 240 The effect of .

2.2. Image.getScaledInstance

This is a Java Native features are another way to resize pictures , It is easy and convenient to use this method to adjust the size of the picture , The quality of the generated image is also good , The code is simple , however This method is not efficient .

/**
 *  Picture zoom 
 *
 * @param srcImagePath   Picture path 
 * @param targetWidth    Target width 
 * @return
 * @throws IOException
 */
public static BufferedImage resizeImage2(String srcImagePath, int targetWidth) throws IOException {
    Image srcImage = ImageIO.read(new File(srcImagePath));
    int targetHeight = getTargetHeight(targetWidth, srcImage);
    Image image = srcImage.getScaledInstance(targetWidth, targetHeight, Image.SCALE_DEFAULT);
    BufferedImage bufferedImage = new BufferedImage(targetWidth, targetHeight, BufferedImage.TYPE_INT_RGB);
    bufferedImage.getGraphics().drawImage(image, 0, 0, null);
    return bufferedImage;
}
// getTargetHeight  Same as  java.awt.Graphics2D  Sample code in

In code Image.SCALE_DEFAULT Represents the algorithm used for image scaling , stay Java doc - Image All available algorithms can be viewed in the document .

3. RGB Gray calculation

We know that the picture is composed of pixels , Each pixel stores color information , Usually RGB Information , So we want to convert each pixel into characters , That is to put the RGB The grayscale expression of information , Different gray levels give different characters to represent .

For example, we divide the gray scale into 10 Level , Select a character from high to low for each level .

'W', '@', '#', '8', '&', '*', 'o', ':', '.', ' '

So how to calculate the gray scale ？ At present, the common calculation method is the average method 、 Weighted mean method 、 Gamma correction method, etc . Here, the mathematical formula similar to the linearity of gamma correction is directly used for calculation , This is also MATLAB、 Pillow and OpenCV Method used .

4. Output character picture

The preliminary preparations have been completed , We have scaled the picture , At the same time, I also know how to put the image on each pixel in the picture RGB The information is converted into gray values , Then we only need to traverse the zoomed image RGB Information , Gray scale conversion , Then select the corresponding character to print .

public static void main(String[] args) throws Exception {
    BufferedImage image = resizeImage("/Users/darcy/Downloads/bingdundun.jpeg", 150);
    printImage(image);
}

/**
 *  Character picture printing 
 *
 * @param image
 * @throws IOException
 */
public static void printImage(BufferedImage image) throws IOException {
    final char[] PIXEL_CHAR_ARRAY = {'W', '@', '#', '8', '&', '*', 'o', ':', '.', ' '};
    int width = image.getWidth();
    int height = image.getHeight();
    for (int i = 0; i < height; i++) {
        for (int j = 0; j < width; j++) {
            int rgb = image.getRGB(j, i);
            Color color = new Color(rgb);
            int red = color.getRed();
            int green = color.getGreen();
            int blue = color.getBlue();
            //  One for calculating RGB The formula of pixel gray 
            Double grayscale = 0.2126 * red + 0.7152 * green + 0.0722 * blue;
            double index = grayscale / (Math.ceil(255 / PIXEL_CHAR_ARRAY.length) + 0.5);
            System.out.print(PIXEL_CHAR_ARRAY[(int)(Math.floor(index))]);
        }
        System.out.println();
    }
}

// resizeImage  Same as the code in part II

Here I choose a picture of an ice pier. , You can see the effect after output .