Architectural: Editing PDF in photoshop creates large file but grainy. Unusable.

[Nomados]

I'm working with high resolution scanned architectural plan pdfs. (Doc: 154M) Opened in Photoshop and then edited using the eraser tool, (hours....) Save, as pdf. 

The resulting PDF is unusable.  Grainy.  There are no save options that I can see to make it better.

Photoshop CC 2015

The file is 4 times larger than the original, yet looks like crap when you zoom in compared to the original.  Hoping to recover all of the work done.

Any suggestions appreciated.

[c.pfaffenbichler]

There are no save options that I can see to make it better.

And what are the option you did use?

Please provide meaningful information.

And how did you open the image anyway?

Did you convert the pdf page (thus potentially damaging it already) or open the embedded image?

[Nomados]

Thanks.
Open PDF in Photoshop CC2015.
Edit
Save (PDF). 
Options unavailable. 

[Nomados]

I mean, I could use Proof Setup and/ or ICC profile, but I really doubt that would help here? 
Please correct me if I'm wrong. 

[c.pfaffenbichler]

Open PDF in Photoshop CC2015.

That seems to be a meaningless statement.

What exactly did you do – convert the pdf page or open the image contained in the pdf?

I mean, I could use Proof Setup and/ or ICC profile, but I really doubt that would help here? 

What is that even supposed to mean?

How did you save the pdf exactly – I mean the complete pdf settings you used?

And to save yourself a lot of typing why don't you provide an original pdf and the result you produced for testing and comparison?

[Mylenium]

It seems you need to read up to understand how PDFs actually work. The "graininess" no doubt is just JPEG artifacts whereas the original PDFs were saved with TIFF-compatibility. As Mr. Pfaffenbichler laready said, it all comes down to which PDF preset you actually used, which contrary to your statement of no options being available are hidden under the "Save Options" link. Again, I think you need to brush up on how to work with PDFs in PS specifically and also in general.

Mylenium

[Test Screen Name]

Go back to your saved PSD. Convert to grey scale colour model if there is no colour. Save as PDF with ZIP compression.

[Nomados]

I appreciate that but I'd prefer to keep the "redlines" as it is a marked up architectural plan. 
I'm just trying to figure out why I am losing the original file integrity.

[Nomados]

As enticing as that "Save Options" link looks, with it's glorious blue link ink, there isn't anything to click there, which is one of the

reasons why i provided the screenshot. 

The "save options" is literally what is presented there.

To reiterate;

Open pdf, edit, save.  Options presented, don't click any because I don't see any relevance to making it any better (open to corrections)
Anything beyond that is spelled out in screenshots. 

Original PDF vs what is saved out of Photoshop as a PDF is vastly different in quality, but larger in files size.  I don't have any option to control that from what I can see. I'm not changing anything; no presets (there aren't any, I'm not processing PDF files from Acrobat, I'm simply saving from Photoshop.)

[c.pfaffenbichler]

Open pdf, edit, save.

When you »open« the pdf are you presented with a dialog window titled »Import PDF«?

If so what did you do exactly?

[davescm]

Hi

After you click save you should get a warning that PDF settings will override your current Save As settings (in practice that means next time you use Save As - save the layers will be unchecked and you will need to recheck it). Then you should see the PDF options dialogue

Dave

[Test Screen Name]

Because you aren't choosing the right options. The default is JPEG compression which is quite unsuitable for architectural plans.

Save PDF files in Photoshop

You haven't showed us your Save PDF options, which appear after you click Save.

[c.pfaffenbichler]

I am still not sure if this is the case here or not but if the OP converted the page instead of opening the image (see screenshot) the file they worked on might already have be damaged.

[PECourtejoie]

Hello, if you cannot provide the file for copyright reasons, please post a screenshot of an smaller area in both the original and the edited files.

But please describe the exact options used both for opening and saving!

[D Fosse]

If this is original vector work, rasterized to jpeg, of all things, somewhere along the way, then no wonder it looks bad. Jpeg should never come near anything with delicate detail, whether design drawings or text or line art or anything similar. The jpeg compression artifacts will destroy it.

[c.pfaffenbichler]

The OP stated

I'm working with high resolution scanned architectural plan pdfs.

so I assume it’s pixel scans.

Why pdfs – who knows?

[Nomados]

I appreciate all responses.
Maybe this is a higher level problem;

I'm using Windows 7 Ultimate. 
It's not an import, options situation; I just right click PDF file, open with; Photoshop. 
No options are presented.  File opens in Photoshop.  I edit the file.  I save the file. 
The subsequent file is grainy and roughly 4 times larger.

If there were options, on either side, I could manage those, as I'm quite familiar. 
That's not the case here, which is why I am asking.

[c.pfaffenbichler · Accepted solution]

When you »Save« »As a Copy« are you presented with the PDF dialog?

Do you keep the layered file?

[c.pfaffenbichler]

Another thing: Please post at least some screenshots to illustrate the difference in appearance already.

[Nomados]

[Nomados]

Saving "copy" brought up the options, thanks!!!

The file is now ~50 times larger than original, and I have multiple copies of it but hey at least it works. 
I'm still curious as to what is behind what's occurring here but I'm gonna let it go. 

Appreciate the help. 
Copy=Options.  Gotit.  

[Nomados]

for posterity;

Screenshot at top, #1

Saved copy with options, no compression; 181MB

#2 Save "out of the box" no options presented; ~24MB

#3 pre edit.  3.3MB

[c.pfaffenbichler]

Saved copy with options, no compression; 181MB

Did you save with »Preserve Photoshop Editing Capabilities«?

That packs all the Layers etc. into the pdf additional to the actual pdf content.

So you might want to keep the layered file as tif, psd or psb and just save a flat copy off of that.

And no compression might be overdoing it, LZW for example provides lossless compression (with longer saving times possibly).

[D Fosse]

You have obvious jpeg compression artifacts here! This is the price you pay for the small jpeg file size.

Never use jpeg for things like this. Sharp transitions get smudged in the compression algorithm. And worse - it's irreversible.

Use any non-destructive file format. Yes, the file gets bigger, but that's just the way it is. In a pinch, you could try PNG, which also compresses, but non-destructively.

[Bo_LeBeau]

I agree that most of the issues are from jpg artifacts, but I also think that the image is being down sampled when resaving as a PDF

See davescm's screenshot in answer 11. Down sampling, compression and image quality settings can all affect the final product.

You mentioned that this was a high resolution scan. Do you know the resolution? Also, on large blueprint scanners there are some settings that can affect the scan quality. Digital printers that can also scan have a much more limited set of controls than stand alone scanners. But it is what it is.

You mentioned spending hours with the eraser tool (it shows in some of your screenshots). You likely could have saved all that time by using a Levels adjustment layer. I know that some people say you should use a Curves adjustment, but the Levels adjustment layer is easier to understand, and since you spent hours with the eraser, easier is better. After all, its not the Mona Lisa, but just a bluepriint. In less than a minute you could have eliminated most of the "schmutz" that you spent hours erasing. Even if it doesn't eliminate it all, what is left over is greatly reduced in the final product. But again, pay attention to: Down Sampling, Compression and Image Quality.  Also some PDF settings will convert your RGB scan into a CMYK image. 4 channels vs 3 channels will mean a bigger file size.

PS: Blueprints are normally scanned as a Multipage PDFs since it is rarely just 1 page being scanned. Architects, Contractors, etc will be upset if they receive 8 separate files of their scanned 8 page blueprint set. They want it all in 1 file.