10-27-2018, 08:07 AM
Quote:and the resulting pdf was stil a 591x984 with 100dpi.
No, you are still confused about image size in pixels and printing resolution. Did you not read when I wrote you can have the PDF at any ppi (dpi for printing) How are you opening the PDF? What application are you using? Are you using Gimp 2.6?
Quote:Installed libreoffice did what you said and the resulting image was a 590x985. On top of that, it was a single image pdf, since when I open the second image it overrides the first one.
I suspect user error. Did you:
Create a page size, 15 cm x 250 cm with zero borders.
Make two pages
Put separate 1772 x 2953 pixels images on each page
Quote:It seems all the programs are generating the same size images. Perhaps it is right and now that is being used correct source images with 300 dpi source, it will be correct? I will do a test soon.
You are looking at them in the same way which is why you see 591x984 with 100dpi.
The important bit is the pixel size of the image encapsulated in the PDF. Large image in pixels = good quality small image in pixels = not so good. Gimp works in pixels but you can print the image at any ppi resulting in different real world sizes. A PDF is a universal format, In Gimp will always open at a default resolution of 100 ppi. Up to you to specify the ppi. Although I do not know if you are using your Gimp 2.6 for this.
Trying another way of looking at the 2 page PDF. Using ImageMagick convert command.
Image 1 1772 x 2953 @ 300 ppi = 120 KB Image 2 1772 x 2953 @ 300 ppi = 300 kb The PDF should be around 420 KB
If the image was scaled down during the creation of the PDF it would be much smaller.
Of course that is a simplistic example, some applications might take a png, convert to a jpg and come up with a smaller PDF but like-for-like the PDF size is the sum of the image sizes.
You can do as many tests as you like but until you understand the relationship between pixel size and printing pixels-per-inch you will keep getting the same outcome.