[英]Unable to down scale gray scale image
我有一個尺寸為256 * 256的灰度圖像,我正在嘗試將其縮小為128 * 128。 我平均要取兩個像素並將其寫入輸出文件。
class Start {
public static void main (String [] args) throws IOException {
File input= new File("E:\\input.raw");
File output= new File("E:\\output.raw");
new Start().resizeImage(input,output,2);
}
public void resizeImage(File input, File output, int downScaleFactor) throws IOException {
byte[] fileContent= Files.readAllBytes(input.toPath());
FileOutputStream stream= new FileOutputStream(output);
int i=0;
int j=1;
int result=0;
for(;i<fileContent.length;i++)
{
if(j>1){
// skip the records.
j--;
continue;
}
else {
result = fileContent[i];
for (; j < downScaleFactor; j++) {
result = ((result + fileContent[i + j]) / 2);
}
j++;
stream.write( fileContent[i]);
}
}
stream.close();
}
}
上面的代碼成功運行,我可以看到輸出文件的大小減小了,但是當我嘗試將輸出文件(原始文件)在線轉換為jpg( https://www.iloveimg.com/convert-to-jpg/raw- to-jpg ),這給我一個錯誤,指出文件已損壞。 我已經從同一在線工具轉換了輸入文件,它可以正常工作。 我的代碼創建了損壞的文件,出現了問題。 我該如何糾正?
PS我不能使用任何直接縮小圖像尺寸的庫。
您的代碼未處理圖像大小調整。
請參閱如何在Java中調整圖像大小 。
我在這里復制一個簡單的版本:
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class ImageResizer {
public static void resize(String inputImagePath,
String outputImagePath, int scaledWidth, int scaledHeight)
throws IOException {
// reads input image
File inputFile = new File(inputImagePath);
BufferedImage inputImage = ImageIO.read(inputFile);
// creates output image
BufferedImage outputImage = new BufferedImage(scaledWidth,
scaledHeight, inputImage.getType());
// scales the input image to the output image
Graphics2D g2d = outputImage.createGraphics();
g2d.drawImage(inputImage, 0, 0, scaledWidth, scaledHeight, null);
g2d.dispose();
// extracts extension of output file
String formatName = outputImagePath.substring(outputImagePath
.lastIndexOf(".") + 1);
// writes to output file
ImageIO.write(outputImage, formatName, new File(outputImagePath));
}
public static void resize(String inputImagePath,
String outputImagePath, double percent) throws IOException {
File inputFile = new File(inputImagePath);
BufferedImage inputImage = ImageIO.read(inputFile);
int scaledWidth = (int) (inputImage.getWidth() * percent);
int scaledHeight = (int) (inputImage.getHeight() * percent);
resize(inputImagePath, outputImagePath, scaledWidth, scaledHeight);
}
public static void main(String[] args) {
String inputImagePath = "resources/snoopy.jpg";
String outputImagePath1 = "target/Puppy_Fixed.jpg";
String outputImagePath2 = "target/Puppy_Smaller.jpg";
String outputImagePath3 = "target/Puppy_Bigger.jpg";
try {
// resize to a fixed width (not proportional)
int scaledWidth = 1024;
int scaledHeight = 768;
ImageResizer.resize(inputImagePath, outputImagePath1, scaledWidth, scaledHeight);
// resize smaller by 50%
double percent = 0.5;
ImageResizer.resize(inputImagePath, outputImagePath2, percent);
// resize bigger by 50%
percent = 1.5;
ImageResizer.resize(inputImagePath, outputImagePath3, percent);
} catch (IOException ex) {
System.out.println("Error resizing the image.");
ex.printStackTrace();
}
}
}
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