我需要一段完整的基于lzw编码实现图像压缩设计与实现的代码
时间: 2023-06-13 13:02:04 浏览: 146
【图像压缩】基于LZW实现图像压缩算法附matlab代码.zip
以下是一个基于LZW编码实现图像压缩的Python代码示例:
```python
import numpy as np
from PIL import Image
def compress(image_path, output_path):
# Load image as numpy array
image = np.array(Image.open(image_path))
# Flatten image into a 1D array
pixels = image.flatten()
# Create dictionary with all possible pixel values
dictionary = {i: chr(i) for i in range(256)}
# Initialize variables
string = ""
compressed = []
# LZW compression algorithm
for pixel in pixels:
string_plus_pixel = string + chr(pixel)
if string_plus_pixel in dictionary:
string = string_plus_pixel
else:
compressed.append(dictionary[string])
dictionary[string_plus_pixel] = len(dictionary)
string = chr(pixel)
# Add last string to compressed output
if string in dictionary:
compressed.append(dictionary[string])
# Save compressed output to file
with open(output_path, "wb") as f:
for code in compressed:
f.write(bytes([code]))
def decompress(input_path, output_path):
# Load compressed file as bytes
with open(input_path, "rb") as f:
compressed = f.read()
# Create dictionary with all possible pixel values
dictionary = {i: chr(i) for i in range(256)}
# Initialize variables
string = ""
decompressed = []
# LZW decompression algorithm
for code in compressed:
code = int(code)
if code in dictionary:
entry = dictionary[code]
elif code == len(dictionary):
entry = string + string[0]
else:
raise ValueError("Bad compressed code: %d" % code)
decompressed.append(ord(entry[0]))
if string:
dictionary[len(dictionary)] = string + entry[0]
string = entry
# Convert 1D array back into image
width, height = np.array(Image.open(input_path)).size
pixels = np.array(decompressed).reshape(height, width).astype(np.uint8)
Image.fromarray(pixels).save(output_path)
# Example usage
compress("input.png", "compressed.lzw")
decompress("compressed.lzw", "output.png")
```
这段代码将输入的图像文件进行LZW压缩,并将压缩后的结果保存到文件中。然后可以使用相同的代码对压缩文件进行解压缩,得到原始图像文件。请注意,这个实现并不是最优化的,可能会存在一些性能问题。
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