将目录下所有.jpg图片转换为.pdf | 调试 ImageMagick

Question

I have found multiple posts regarding this issue and everyone is recommending ImageMagick but for me, it doesn't seem to work as intended and I don't see too many docs on their site regarding.jpg->.pdf conversion.

Is there some alternative, preferably CLI tool?

Or can I somehow debug why ImageMagick doesn't work for me? I don't get any errors I just get corrupted files as a result.

My usecase

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My os is Windows and I have 64.jpg files called 0.jpg, 2.jpg, ... 63.jpg and I would like to merge all those images into one.pdf file.

I have tried these commands:

magick 0.jpg 0.pdf

but in both cases, I am unable to open the out.pdf file because it is corrupted. I have noticed that I can only convert 0.jpg file to pdf correctly but when I try to convert any other of my 64 jpg files then as a result I am getting a corrupted.pdf file
For example:
This gives me the correct.pdf:

magick 2.jpg 2.pdf

but this gives me corrupted.pdf:

 magick 2.jpg 2.pdf

I assume that this a reason why I can't merge all of the files into one not corrupted.pdf file and my assumption is that there is something wrong with the rest of my.jpg files but I have no idea how to debug this issue. Every other.jpg file looks exactly the same as the one.jpg I can convert and all of them open without issues.

magick identify -verbose foobar.jpg results:

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I can convert 0.jpg file to.pdf correctly but 2.jpg results in corrupted.pdf. There are some apparent differences but I am not sure what those properties mean in the context of.jpg ->.pdf conversion

Answer 1

One thought is that someone has converted the grayscale image to color with 3 equal channels so that it IM says it has colorspace RGB. However, the JPEG colorspace tag is 2, which says it has no specific colorspace.

Properties:
    date:create: 2021-04-01T17:29:06+00:00
    date:modify: 2021-04-01T05:18:58+00:00
    exif:ExifOffset: 46
    exif:ExifVersion: 48, 50, 50, 48
    exif:PixelXDimension: 960
    exif:PixelYDimension: 1508
    exif:Software: Google
    jpeg:colorspace: 2
    jpeg:sampling-factor: 2x2,1x1,1x1

From the JPG docs

ColorSpace

0 = Bi-level 
1 = YCbCr, ITU-R BT 709, video 
2 = No color space specified 
3 = YCbCr, ITU-R BT 601-1, RGB 
4 = YCbCr, ITU-R BT 601-1, video 
8 = Gray-scale 
9 = PhotoYCC 
10 = RGB 
11 = CMY 
12 = CMYK 
13 = YCCK 
14 = CIELab

It is possible that this conflict or lack of colorspace may confuse certain viewers after the file is imbedded in a PDF vector shell.

Answer 2

Thank you @Mark Setchell for pointing me in the right direction by sharing this command:

magick identify -verbose XXX.jpg

My images are grayish so I don't know why majority of the files has sRGB colorspace but after converting colorspace to Gray I can convert them to.pdf properly (I don't see any difference when I open up my.jpgs after conversion to grayscale).

Using this command I can change colorspace to Gray :

magick 2.jpg -colorspace gray gray2.jpg

Then I can convert "grayscale".jpgs to.pdf by simply:

magick gray2.jpg gray2.pdf

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PS If anyone has some better solution I will gladly accept it but if nothing shows up I am going to accept this

@fmw42 Here is a .zip file that contains

• 20.jpg - source image
• 20.pdf - corrupted pdf after running >magick 20.jpg 20.pdf
• gray20.jpg - source image converted to gray by >magick 20.jpg -colorspace gray gray20.jpg
• gray20.pdf - source image converted to.pdf after changing colorspace to gray first by >magick gray20.jpg gray20.pdf

Keep in mind that this image is from some weird manga but I have tried to pick the most normal page (it was harder than it seemed to be but this image itself is not nsfw)