Scribus export to PDF results in a large file size (compared to the included JPEG)

Question

I am trying to add a JPEG image to a Scribus document, and then to export it as PDF; the file size of the resulting PDF should not be much higher.

I just added a frame for an image, loaded the JPEG file into it, and adjusted the image size to the frame's size.

Then I exported it as PDF, and the file size of the PDF was much higher than the JPEG file. The JPEG file has a size of 165 KB, and the PDF's size is 1 MB.

I tried to do the same using gimp, and there the resulting file is 1 MB as well, so same problem.

Then I tried imagemagick's convert; there the resulting file is 177 KB, using:

convert 1.jpg 1.pdf

As for Scribus, I tried to change some settings in the PDF export (compression method, max. resolution etc.). This did reduce the file size, but image quality got worse.

How can I include a JPEG image in Scribus, and then export it "as-as" to PDF, without any real transformation, except for scaling (which could be stored just as a factor)?

Update

• I am using Scribus 1.4.6 on Linux
• I cannot upload my JPEG file, but I could reproduce it using this file: The JPEG file size is 220 KB, the resulting PDF is 1 MB.

Update 2

This issue has been crossposted to the Scribus issue tracker

Answer 1

I just gave it a try: in Scribus 1.5, including this test image with the automatic settings, gives me a Pdf that is 1Kb bigger than the image itself and pdfimages can extract a jpg that is exactly as big as the original image.

In my experience for jpg images that are somehow ok, the best is to get Scribus not to touch the image during the Pdf export.

You can test with the same image and if you get the same results as I do, but still a much different size with the new settings and your image, you're welcome to share a jpg and a Scribus file that show the problem, so that we can check with it.

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Edit: as you might have read in the comments to the ticket, the reason why Scribus cannot include the image you linked is that it's a grayscale jpeg. Scribus does not 100% support them.

Jean has given a list of more reasons why a jpeg file might be resampled when included into a pdf. One of them might apply to the image you're using in your project.

Answer 2

the resulting PDF should not be much higher

Well, that is not true. Let me explain.

A PDF can have different settings on compression of the images.

You can have some images not compressed at all, some with lossless compression and some with JPG compression.

If you choose JPG compression, and you did not modify anything on the images, yes, there is a chance the JPG compression, therefore the file size will match. But if you choose another type of compression or none at all, or you set up the RGB files to be converted to CMYK for example, the file will be larger.

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Answering the question. Match the compression data with the characteristics of the JPG file. Mainly, use JPG compression and maintain the color mode of the embedded files.