ImageMagick的identify
命令行工具提供有关图像文件中包含的采样图像的信息。我试图理解“16”在它报告的内容中意味着什么。
我很确定这是一个单色图像,只有一位内容和每像素一个透明位,所以我不明白“16”在这里扮演的角色。是1代表65535的灰度级“值”(即在这种情况下全白)?或者这是否与1位内容通道和1位alpha /透明通道打包成16位字有关?
在非详细模式下,它会报告:
20140123124823096.pdf PDF 1008x612 1008x612+0+0 **16-bit Bilevel Gray** 77.2KB 0.000u 0:00.000
在详细模式下,它会报告以下内容:
Image: 20140123124823096.pdf
Format: PDF (Portable Document Format)
Mime type: application/pdf
Class: DirectClass
Geometry: 1008x612+0+0
Resolution: 72x72
Print size: 14x8.5
Units: Undefined
Type: Bilevel
Base type: Bilevel
Endianess: Undefined
Colorspace: Gray
Depth: 16/1-bit
Channel depth:
gray: 1-bit
alpha: 1-bit
Channel statistics:
Gray:
min: 0 (0)
max: 65535 (1)
mean: 60686.5 (0.926017)
standard deviation: 17153.4 (0.261744)
kurtosis: 8.59646
skewness: -3.25522
Alpha:
min: 65535 (1)
max: 65535 (1)
mean: 65535 (1)
standard deviation: 0 (0)
kurtosis: 0
skewness: 0
Colors: 2
Histogram:
45640: ( 0, 0, 0,65535) #000000000000 graya(0,1)
571256: (65535,65535,65535,65535) #FFFFFFFFFFFF graya(255,1)
Rendering intent: Perceptual
Gamma: 0.454545
Chromaticity:
red primary: (0.64,0.33)
green primary: (0.3,0.6)
blue primary: (0.15,0.06)
white point: (0.3127,0.329)
Background color: graya(255,1)
Border color: graya(223,1)
Matte color: graya(189,1)
Transparent color: graya(0,0)
Interlace: None
Intensity: Undefined
Compose: Over
Page geometry: 1008x612+0+0
Dispose: Undefined
Iterations: 0
Compression: Undefined
Orientation: Undefined
Properties:
date:create: 2014-01-23T12:41:20-08:00
date:modify: 2014-01-23T12:41:20-08:00
pdf:HiResBoundingBox: 1008x612+0+0
pdf:Version: PDF-1.4
signature: 94e55396cd1b4dea139dcb39458ada0c904d80810722d7c03a62691d710755ab
Artifacts:
filename: 20140123124823096.pdf
verbose: true
Tainted: True
Filesize: 53.1KB
Number pixels: 617K
Pixels per second: 15.42MB
User time: 0.040u
Elapsed time: 0:01.039
Version: ImageMagick 6.8.7-3 2013-11-20 Q16 http://www.imagemagick.org
更新:事实证明,ImageMagick工具报告的信息实际上并不是PDF文件中有关图像的信息,但显然有关图像经过某种形式后的信息内部转型!我在文本编辑器中查看了PDF文件,可以看到它是200 dpi(合法大小)的每像素1位单色图像,而不是具有ImageMagick报告的alpha通道的72 dpi图像。所有这一切,我仍然很好奇,即使在ImageMagick的人造世界中,这意味着什么。
以下是对PDF中实际存在的图像的描述:
<</Type/XObject
/Subtype/Image
/Width 2800
/Height 1700
/BitsPerComponent 1
/ColorSpace/DeviceGray
/Filter /CCITTFaxDecode
/DecodeParms <</Columns 2800 /Rows 1700>>
/Length 142719
>>