I’m looking for help and guidance with creating reduced file size PDFs from CorelDraw (Standard 2020). I am trying to publish an adult coloring book and I am limited to a 20MB file size. I have 55 designs that are all black and white line drawings. The Corel file is made up of importing these JPG designs into it, one per page. The Corel file is 100MB. When I export it to a PDF, the resulting PDF file is roughly 28MB. The file size reducer in Acrobat only can get it down to about 24MB. I don’t want to lose any of the line detail, so I’ve been trying to manipulate the JPG files to make this work. I cannot for the life of me figure out what is the best format for the JPG files to get the desired result. Low DPI and small dimensions? Low DPI and large dimensions? High DPI and large dimensions? High DPI and smaller dimensions? I started with 72 DPI files in Corel. This is the 100MB file. Then I replaced a bunch of the JPG files in Corel with 300 DPI files, and the Corel file went up to about 239MB, but the PDF export gave me roughly the same file sizes as before. Does anyone have any best practices for creating a smaller PDF file size with line art? I appreciate any suggestions.
How are you originally creating the black and white line drawings? Are they starting out as some sort of vector content, that you are then converting to .JPG?
Hello "Eskimo". The original files are exported from an app and are already in JPG format. They start at about 4000x4000 pixels and are about 7MB. So I already have to reduce them down.
There are PDF presets, document distribution downsamples images to 96 dpi. Since you don't tell me how you're going to view or use the PDF exact settings are impossible.
In the objectvtab of the PDF dialog you can set the resolution of the images in the PDF.
If is say downsample over 300 the resolution of higher resolution images will be reduced to 300, if you need lower change the values. For desktop print 200 usually works.
That's assuming the imagescare above 200 dpi to start.
BHarder said:The original files are exported from an app and are already in JPG format.
The reason I asked is that, from the standpoint of file size, .JPG might not be the best format for line art.
For some types of graphics, lossless compression (possible with .PNG) produces better results than the lossy compression of .JPG.
If you are limited to .JPG, then the level of compression can make a big difference when it comes to file size (sometimes involving a compromise in image quality; depends on the image).
it's for web or for print? if it's for web you don't need to use 300 dpi at all. Moreover, you can use JPG and increase file compression, such as 50%, in order to create a smaller file
The PDF is actually for print. that is why I'm worried about losing line clarity.
Inkjet print needs about 200 DPI at placed size, press print 300 DPI.
For coloring books, black & white line drawings should be vector shapes. Reasons...
JPEG compression shouldn't be even be in the conversation as part of an end goal.If anything... if this guy prefers hi-res monochrome bitmaps for export, he should be using a lossless run-length compression method such as LZW in the PDF export options.
See attached 3-page CDR in the ZIP
4628.flower.zip
I agree, the days of using vectors in raster editors is mostly gone.
Here are the single PDF exports; Either will output fine visually for this guy's purposes.One example is 600DPI monochrome.But the vector version is 1/3 smaller in file size, clearer, and much more editable if the artist chooses to.
flower-pdf.zip
BHarder said:. I cannot for the life of me figure out what is the best format for the JPG files to get the desired result
First - study the original images for quality. upsampling images is almost always a bad idea unless there's a reason to. And there are rare reasons, and we're glad you're asking. :-)
if your end visual goal is black and white only, the 2 key things are to dispose of the excessive bit depth in your images, so that each pixel is eventually either black or white. No need for RGB, CMYK, or Grayscale for color models at the end.
for something like random coloring book art - I'd likely upsample to 600 grayscale - at first.
Then adjust using BCI, tone curves, to get nice crisp lines. Check out the median, maximum, minimum effects. These effects are resolution dependent. and also color model dependent. You just have more control over pixels at higher resolutions for these tweaks.
zoom in - scrutinize the art until you are happy.
Convert to "nice" monochrome image, use line art at medium threshold. CorelDRAW 2020 presents monochrome images poorly in enhanced mode. Try normal.
then export using LZW compression. the PDF will be much smaller. This is the hi-resolution monochrome bitmap route.
but.... the best way is vector shapes:
Sadly, Trace in Coreldraw 2020 for hi-resolution monochromes was brutally slow. I wasn't quickly getting the result I wanted. Trace was thinking waaaay too hard about something.
So... I ended up using Inkscape (free) which instantly traced my 600 DPI monochrome image into a single vector shape that I wanted. Then I reduced the nodes (reduced the threshold for auto-reduce in the inkscape behavior section). Then pressed CTRL+L to reduce nodes... (inkscape reduce node function is too aggressive by default.)
Then I exported it as a postscript file and brought into CorelDRAW.
the vector shape PDF is in another post in this thread. I think it's 100KB.
Why do you have a 20MB limit?