173 lines
4.5 KiB
Python
173 lines
4.5 KiB
Python
from math import floor
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# 十六进制转十进制
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def byteSize(begin, length):
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size = 0
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for i in range(length):
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size += imgBytes[i + begin] * 16**(2 * i)
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return size
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# 十进制转十六进制
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def sizeByte(size, length):
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b = []
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while (size):
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b.append(size // 16**((length - len(b) - 1) * 2))
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size %= 16**((length - len(b)) * 2)
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b.extend([0] * (length - len(b)))
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return b[::-1]
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# 输入数据
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img = input("请输入图片路径：")
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new_width = int(input("请输入新宽度(px)："))
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new_height = int(input("请输入新高度(px)："))
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# img = 'imgs/24.bmp'
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# new_width = 128
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# new_height = 128
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# 读入图片
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with open(img, 'rb') as f:
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imgBytes = f.read()
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# 文件头处理
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# 检验文件头是否为 BM
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if (imgBytes[0] != 66 or imgBytes[1] != 77):
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print("当前文件非 BMP 格式")
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exit()
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fileSize = byteSize(2, 4) #文件头中的文件大小
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dataStart = byteSize(10, 4) #文件头中的数据开始字节
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# bmp 文件头
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headerSize = byteSize(14, 4)
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width = byteSize(18, 4)
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height = byteSize(22, 4)
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nbplan = byteSize(26, 2)
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bpp = byteSize(28, 2)
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compression = byteSize(30, 4)
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imageSize = byteSize(34, 4)
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# 调色板不做处理
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# 变量预处理
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pixels = []
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for i in range(height):
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pixels.append([])
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rowLength = width
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rowLength *= bpp // 8
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while (rowLength % 4 != 0):
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rowLength += 1
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# 计算像素点
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i = dataStart
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currentRow = 0
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while (currentRow < height):
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currentCol = 0
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while (currentCol < width * (bpp // 8)):
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if (bpp == 32):
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pixels[currentRow].append({
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'r':
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imgBytes[dataStart + currentRow * rowLength + currentCol],
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'g':
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imgBytes[dataStart + currentRow * rowLength + currentCol + 1],
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'b':
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imgBytes[dataStart + currentRow * rowLength + currentCol + 2],
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'a':
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imgBytes[dataStart + currentRow * rowLength + currentCol + 3]
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})
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currentCol += bpp // 8
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else:
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pixels[currentRow].append({
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'r':
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imgBytes[dataStart + currentRow * rowLength + currentCol],
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'g':
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imgBytes[dataStart + currentRow * rowLength + currentCol + 1],
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'b':
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imgBytes[dataStart + currentRow * rowLength + currentCol + 2]
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})
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currentCol += bpp // 8
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currentRow += 1
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# 读入图片为像素数组完成
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# 缩放图片
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# 变量预处理
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scale_w = new_width / width
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scale_h = new_height / height
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newpixels = []
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for i in range(new_height):
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newpixels.append([])
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# 计算新像素
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currentRow = 0
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while (currentRow < new_height):
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currentCol = 0
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while (currentCol < new_width):
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newpixels[currentRow].append(pixels[floor(currentRow / scale_h)][floor(
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currentCol // scale_w)])
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currentCol += 1
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currentRow += 1
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# 处理新文件
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newimgArray = [66, 77]
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rowLength = new_width
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rowLength *= bpp // 8
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while (rowLength % 4 != 0):
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rowLength += 1
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# 新文件头
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new_fileSize = 54 + rowLength * new_height #文件头中的文件大小
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newimgArray.extend(sizeByte(new_fileSize, 4))
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newimgArray.extend(sizeByte(0, 4))
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new_dataStart = dataStart
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newimgArray.extend(sizeByte(new_dataStart, 4))
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# 新 bmp 文件头
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new_headerSize = headerSize
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newimgArray.extend(sizeByte(headerSize, 4))
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new_width_b = sizeByte(new_width, 4)
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newimgArray.extend(new_width_b)
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new_height_b = sizeByte(new_height, 4)
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newimgArray.extend(new_height_b)
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new_nbplan = nbplan
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newimgArray.extend(sizeByte(new_nbplan, 2))
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new_bpp = bpp
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newimgArray.extend(sizeByte(bpp, 2))
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new_compression = compression
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newimgArray.extend(sizeByte(new_compression, 4))
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new_imageSize = rowLength * new_height
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newimgArray.extend(sizeByte(new_imageSize, 4))
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# 调色板不做处理
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newimgArray.extend(sizeByte(0, new_headerSize + 14 - len(newimgArray)))
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for i in range(len(newpixels)):
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row = newpixels[i]
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for col in range(len(row)):
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if (new_bpp // 8 == 3):
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pixel = [
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newpixels[i][col]['r'], newpixels[i][col]['g'],
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newpixels[i][col]['b']
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]
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else:
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pixel = [
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newpixels[i][col]['r'], newpixels[i][col]['g'],
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newpixels[i][col]['b'], newpixels[i][col]['a']
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]
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newimgArray.extend(pixel)
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newimgArray.extend(sizeByte(0, rowLength - len(row) * (new_bpp // 8)))
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# 写入新的文件
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newimgBytes = bytes(newimgArray)
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with open(img[:-4] + "_new" + img[-4:], 'wb') as f:
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f.write(newimgBytes) |