python读取bmp图片_用Python读取bmp文件

我意识到这是一个老问题，但我自己解决这个问题时发现了这个问题，我想这可能会在将来帮助别人。

实际上很容易将BMP文件读取为二进制数据。当然，这取决于你需要支持的范围有多广，需要支持的角落案例有多少。

下面是一个简单的解析器，它只适用于1920×1080 24位BMP(类似于从MS-Paint保存的)。但它应该很容易扩展。它以python列表的形式输出像素值，比如红色图像的(255, 0, 0, 255, 0, 0, …)。

如果您需要更强大的支持，这里有一些关于如何正确读取这个问题的答案中的头的信息：How to read bmp file header in python?。使用这些信息，您应该能够使用所需的任何特性扩展下面的简单解析器。

如果你需要的话，维基百科上还有更多关于BMP文件格式的信息。def read_rows(path):

image_file = open(path, “rb”)

# Blindly skip the BMP header.

image_file.seek(54)

# We need to read pixels in as rows to later swap the order

# since BMP stores pixels starting at the bottom left.

rows = []

row = []

pixel_index = 0

while True:

if pixel_index == 1920:

pixel_index = 0

rows.insert(0, row)

if len(row) != 1920 * 3:

raise Exception(“Row length is not 1920*3 but ” + str(len(row)) + ” / 3.0 = ” + str(len(row) / 3.0))

row = []

pixel_index += 1

r_string = image_file.read(1)

g_string = image_file.read(1)

b_string = image_file.read(1)

if len(r_string) == 0:

# This is expected to happen when we’ve read everything.

if len(rows) != 1080:

print “Warning!!! Read to the end of the file at the correct sub-pixel (red) but we’ve not read 1080 rows!”

break

if len(g_string) == 0:

print “Warning!!! Got 0 length string for green. Breaking.”

break

if len(b_string) == 0:

print “Warning!!! Got 0 length string for blue. Breaking.”

break

r = ord(r_string)

g = ord(g_string)

b = ord(b_string)

row.append(b)

row.append(g)

row.append(r)

image_file.close()

return rows

def repack_sub_pixels(rows):

print “Repacking pixels…”

sub_pixels = []

for row in rows:

for sub_pixel in row:

sub_pixels.append(sub_pixel)

diff = len(sub_pixels) – 1920 * 1080 * 3

print “Packed”, len(sub_pixels), “sub-pixels.”

if diff != 0:

print “Error! Number of sub-pixels packed does not match 1920*1080: (” + str(len(sub_pixels)) + ” – 1920 * 1080 * 3 = ” + str(diff) +”).”

return sub_pixels

rows = read_rows(“my image.bmp”)

# This list is raw sub-pixel values. A red image is for example (255, 0, 0, 255, 0, 0, …).

sub_pixels = repack_sub_pixels(rows)