PNG conversion to PDF – Black & White ONLY – Ghosting despite all adjustments tried

[Retired HVAC]

Hello all;

Members; please advise if I am performing this task incorrectly. I am trying to convert scanned drawings and electrical schematics and having a ghosting problem in the final step.

1.       Scan image as .PNG in 300x300 dpi

2.       Open in Paint.Net (the best!)

3.       Zoom in and spend much time clearing and cleaning up everything

4.       Use the Adjustments as follows:

·       Black and White – YES

·       Brightness/Contrast – Default (0/0) and also tried -100/+100 and +100/+100

·       Auto-Level – YES

The image presented on the screen is excellent, even at 3200%. There is no shadowing; just perfect black and white. Zero issues at this point.

 

During the cleanup process I strip the .PNG of all bit-mapped text and circular images. My intent is to add all of these attributes back when I open the image in PDF format. Adobe Reader (or Foxit) can create perfect text and circles and shapes as it is vector graphics (I think that what you all call it) so I end up with a gorgeous drawing or schematic created with the best of both worlds; Paint.Net for the line work / PDF for the shapes and text.

 

Now comes the part that creates an issue for me. When I select “Print” the PNG image I use a PDF printer; PDF995 @ 300x300 dpi for example. When the image is created the black and white lines always have shadows. They are very slight but they are there.

 

I also have tried Windows XPS Document Writer and then PDF print, PaperPort, and finally Microsoft Print to PDF. All suffer the same malady. Resolution adjustments do not help.

 

Any suggestions beside the ones that are already posted on the excellent forum? I have tried everything and maybe this is just the way it is. Thanks for your time.

[Reptillian]

Are those shadows in pixel form?  Personally,  I would almost never use raster graphic softwares to make PDFs.  I almost always use a combination of Scribus,  Inkscape,  and Affinity Designer to make my PDFs,  and for very good reasons. The only time when raster graphics are ever acceptable for print if that you plan to print it right away without elements that are just better off with vector softwares,  or you plan to mix actual vectors with raster graphics.

Edited July 29, 2018 by Reptillian
Fixing this post until it looks good enough for me...

[Ego Eram Reputo]

Can you upload a sample of the finished image for us to have a look at?

[Retired HVAC]

Hello Reptillian;

I can't tell if the shadows are pixels as they are only showing in the PDF. I see no shadowy pixels in the PNG.

I will check out the programs you have suggested. I haven't looked yet, but are they free?

I did try something different that worked OK. It required the use of MS Visio.

When I opened the Paint.Net PNG in Visio the shadows were gone! Lines were just a wee bit fuzzy (same as the PNG); but no dang shadows.

I purchased Visio thru a MS HUP. I am fortunate that I grabbed this for $9.95 vs. $250. Ouch!  So I'm good now that I know to use Visio in the future.

This does not help our other Paint.Net users that only have access to free programs like the ones I was using and not having any luck with.

 

Hello Ego Eram Reputo;

I believe I have uploaded the files that are pertinent. The .PNG is great as you will see. Crisp black and white. The PDF conversion, once you zoom in very close, have the shadows as I can them "hugging" the line work. I can't provide the Visio image as it is not supported as downloadable.

 

All;

I have exceeded the upload limit otherwise I would have included the final product which is the Visio file converted to PDF and is looking good.

So to recap the process that works if you have access to Visio is:

1. Scan image as .PNG in 300x300 dpi
2. Open in Paint.Net (the best!)
3. Zoom in and spend much time clearing and cleaning up everything
4. Use the Adjustments as follows:

• Black and White – YES
• Brightness/Contrast – Default (0/0) or what ever setting creates a shadow-free black and white image
• Auto-Level – Yes

Save work a PNG

1. Open PNG in Visio
2. Add all the circles and text
3. Select "Save as PDF" (after first saving as a .vsdx file!)
4. And there you go. Good line work thanks to Paint.Net and nice vector graphics and text thanks to Visio

So I guess my final question is why would Visio make a very good, shadow free image from a Paint.Net PNG, but the PDF printer programs make shadowy ones?

Thanks all for the reply!

Converted to PDF using PDF995.pdf

[Reptillian]

3 hours ago, Retired HVAC said:

Hello Reptillian;

 

I will check out the programs you have suggested. I haven't looked yet, but are they free?

 

Affinity Designer is not free,  but Inkscape and Scribus are free.  In your case, Inkscape tracing would be perfect with the use of pixel snap extension.  Of course,  you have to clean up with something like Paint. NET before converting to vector form. It'll take more time,  but your work will be transferable at any scale.