Merging chopped–up sections of circuit diagrams from PDF manuals?

[Chris55000]

Hi!

All too often, innumerable S.M. pdf files have big circuit or layout diagrams chopped up into small A4 (or even smaller sometimes!) PDF pages because whoever originally scanned a paper original had no access to a large format scanner!

Is there any method of overlaying/stitching the PDF pages together to recreate the original large sheet, or is the PDF format by itself not designed for that?

Most "pdf merge" tools simply merge two distinct sets of pages into a new pdf file, rather than actually overlaying image data!

Has anybody achieved this by free means, or does the raw image data have to be extracted from the PDF first?

The latest S.M. I got like this is for a Philips "PM3382 Revised" (originally Philips code 4822 872 05356) and with anything up to five sections per diagram with over 150 large diagrams in the original paper book, redrawing them is out of the question!

Chris Williams

[Cruisin Marine]

I guess you could use screen capture software like lightshot and "stitch" them together in photo editing software like photoshop etc.

[Dickie]

I've used "PaintShop Pro" (free version) to do this.

[kevinaston1]

Provided the PDF file is not protected, Corel will import it.

Once it is on the screen, pages can be moved around, laid out and stitched as needed, using whatever page size is necessary for the drawings, Corel will then save it as a PDF of your naming.

If it is a one off project, you can download an evaluation copy of Corel Graphics Design free for a month, otherwise you must pay for it.

[Tim]

How times have changed. I remember printing out and sellotaping the various pages of the Decca Bradford circuit diagram together when I was a lad, in order to work on our telly. Literally cut & paste!

[Synchrodyne]

I don’t know whether there are any free applications which do what you want. Mostly I use a very old edition of Photoshop, specifically the Photomerge Panorama Interactive Layout option. 90% of the time it works well. Squaring up and edge trimming of the documents to be merged helps it along. One can start with .pdf documents, and specify the same for output, although I tend to opt for .png. Where the overlap between the elements is too small for automatic merging, one can do it manually. More than two documents at a time can be merged, but the more there are, the greater the likelihood of crazy results.

Sometimes the two or more parts of the schematic or whatever have acquired slightly different scales during original scanning, enough for Photoshop not to work, and this can be a bit of a pain in the derriere. One approach is to resize one or the other using Irfanview, and keep trying until you get it right – i.e. Photoshop will do the merge. Irfanview will work with .pdf, but there seems to be a quality loss. So there it is best to first convert to .png using something else. Photoshop does this very well, and PDF Converter Professional is nearly as good. One can also frig around in Paint to merge two documents of slightly differing scale, and here one has direct control of overlaps. But I don’t do that often enough to remember the steps, so each time is, as they say, “a whole new experience”. Differing scales should not be an issue with sectioned schematics from original manuals, though.


Cheers,

[Duke_Nukem]

There are free on-line sites that can extract images from unprotected PDFs, I've used https://www.extractpdf.com/ before now. I use Paintshop Pro or Paint.NET to do stitch images together (I did try GIMP - it can do it - but it requires a significantly larger swear box).

When I've scanned large TV manual schematics, on my A4 scanner it was quite a faff. Scan in sections, rotate cos they are never quite straight, stitch together (including resize as rotate can alter scaling) and then when its all one big sheet I'd ... yes ... split them up into sections again! Why ? Well if the whole schematic were on a single page and printed out it'd be unreadable.

TTFN,
Jon

[Electronpusher0]

I use the "Draw" program in the Libre office suite of programs.
If the original was scanned you can do as you want and overlay the pdf overlaps to recombine them.

You open the first part pdf in Draw, then change the page size to accomodate the next. Open the second part (this will open it as a second drawing) select and copy the second part and paste it into the first, then move and resize until aligned.

If the original pdfs have been generated by a drawing program rather than scanned then "Draw" allows you to edit individual elements.

Even scanned pdfs can be "edited" by adding text and graphics and using white, borderless boxes to hide parts you want to erase.

For example I attach the schematic /3 version of the MHSVT that I created by modifying the /4 schematic.

Peter

[G6ONEDave]

Years ago when I used to supply service info mail order I had the same problem with oversize circuit diagrams and even the odd text or picture page. Back then the copied page edges never lined up, which meant an overlay area had to be allowed for. I found the minimum overlay needed was 1" (25.4mm) and would try for upto 2" (50.8mm), this would g/tee enough overlay to allow for the cut and join with sellotape method. This was with an A3 photocopier and the problem was caused by the optics. The lenses did not produce a linear image over 100% of the scan, the edges were generally off by a few %, not a lot and not detectable on a single sheet but always a problem when stitching 2 or more pages together. It could be somewhat of a challenge when doing A2, A1 and A0 size pages, because every edge of the A3 copies had size errors. The only other way to solve this problem was to take the original to a large stationers/printers and get them to scan and print it, for a fee of course.

Modern scanners seem a lot better in getting edges to align, although there will always be a scan that does not line up correctly. My experience is that usually it's down to improper positioning of the original on the scanner glass. I do have an A3 multifunction printer that has an A3 scanner and always try to give a large overlay, so that any recipient who wants to print out the pdf images has enough duplicated area to play with, incase of any edge size issues.

Something else to be aware of is that not all service info is on A4, A3 etc paper sizes, quite a lot is on quarto, letter, foolscap or other imperial page size formats, so you need to alter the scan page size, so as not to miss edges from the original when scanning to pdf or jpeg. Luckily the scanner software has facility for this situation, at least mine does.

Dave

[Junk Box Nick]

My method is to open the PDFs in Photoshop (I have a full but old version) – in the case of linework at high resolution usually 600dpi – and expand the canvas of what will be my final version and bring the other PDFs files over on layers.

The transform tool in Photoshop with allow you to adjust a layer if the original is trapezoid from, say a poor scan. In addition to enlargement and reduction you can shear or use a corner handle to pull out a distortion. You will have to do this in greyscale mode in Photoshop as you can’t use the transform tool in bitmap – at least not in my version. Of course, if the original was produced in a drawing program rather than a scan this won’t be an issue as everything should line up.

Of course Photoshop is now rentware though it’s possible that the free photo-editiong programs have similar facilities.

Another method is to place the PDFs, as you would with a photograph, in a page layout program such as QuarkXpress or Adobe InDesign, or a drawing program like Adobe Illustrator, if you have one of those available, and crop the picture boxes to align. Again free programs may allow you to do this as it is a fairly basic process but adjusting slightly distorted scans to line up will be more of a problem.

Incidently, Affinity Photo is a relative inexpensive one-off payment licence that offers professional capability that rivals and in some processes out-performs Photoshop. The Affinity suite also includes a drawing program Affinity Designer, and a page layout program Affinity Publisher. Many pros are moving over to this suite to escape the Adobe rental model.

[MotorBikeLes]

I am with Electronpusher. I use Libre office DRAW. It will open a pdf directly. You can crop if required, and expand or contract in either x or y directions, or by grabbing a corner, keep the x:y ratio constant.
If you open a second draw display, you can copy and paste from the first to the second with no change of size or location. Then copy in another section as required. Export directly as a pdf when you have finished.
You can operate in default A4, or A3 or a wide range of sizes. I know you don't have a working A3 scanner, but probably have an A3 printer so working in A3 then printing out puts you way ahead of where you started.
I am useless at learning to used different software, but have used libre (previously Open Office, previously Star Office etc.) for maybe 15 years now. I bumbled through for the first 10+ years, then learned what F4 does, and now am much more productive. Loads of motor cycle modification drawings, as well as the odd circuit diagram.
Les.

[Chris55000]

Hi!

Dave and Les, thank you both for your input on this!

I do have a Full Affinity Designer Licence and the Workbooks for Affinity Photo, Affinity Designer and Affinity Publisher!

I remember when I posted the Service Manual for the Gould OS4000 Oscilloscope back in 2008 I used an Epson Scanner and the software that came with it, alas to say Epson software has gone distinctly downhill in terms of usefulness and facilities offered since then!

I'll have to read through all the posts and see which is the easiest method to try – is it still possible to buy an old version of (non–rentware!) Adobe PS on CD, and if so, what's the earliest version should I look for?

Chris Williams

PS!

Will "Photoshop Elements", the cut–down version, stitch together layer data from the diagrams as described earlier, or does it need the full P.S.?

[Chris55000]

Hi!

[OUOTE]

For example I attach the schematic /3 version of the MHSVT that I created by modifying the /4 schematic.

[/QUOTE]

Evening Peter!

You don't need to use yukky Arial lettering on your revised drawing – I have posted the exact Uno Stencil Lettering Mullard lettered it with originally on this Forum – it's called "Uno Stencil Alphabet BU" and in TTF – refer to my post "British Vintage Drawing Lettering Now Available" for the full UNO Fonts Pack!

Chris Williams

[jimmc101]

Where the diagram is part of a complete manual, I use PDF-Xchange editor to take a snapshot of the part diagrams I want to stitch, resolution can be adjusted up to 2400dpi although file size becomes excessive at this setting.
Irfanview to save them in TIF format and Image Composite Editor (ICE) from Microsoft Research to stitch the parts together.
ICE can automatically adjust the diagrams to match, although it is best to keep the overlap of the snapshots fairly low before importing or it gets confused.

All programs are free, PDF-Xchange editor works in free mode without registration.

ICE has been abandoned by Microsoft, but still works with the latest version of Windows 10. The last version was 2.0.3, there is no official download but I found one here.
I am wary of downloading from unknown sources but I have checked the file hash (MD5) E55FEC9A014EFBD4F3EDBF3157A5EDC5 against my original download (in 2016) direct from Microsoft.

I've attached a diagram stitched from 3 parts which shows how well ICE has matched the parts without manual adjustment. ( I've had to zip it to upload to the forum without loosing too much resolution)
For reference the originals are an page 171 of the manual here (! 22MB download).

Jim

[Electronpusher0]

Originally Posted by Chris55000

Hi!

Evening Peter!

You don't need to use yukky Arial lettering on your revised drawing – I have posted the exact Uno Stencil Lettering Mullard lettered it with originally on this Forum – it's called "Uno Stencil Alphabet BU" and in TTF – refer to my post "British Vintage Drawing Lettering Now Available" for the full UNO Fonts Pack!

Chris Williams

Thanks Chris, I'll give it a try.

Peter

[Junk Box Nick]

Originally Posted by Chris55000

PS!

Will "Photoshop Elements", the cut–down version, stitch together layer data from the diagrams as described earlier, or does it need the full P.S.?

I can’t say as I’ve only ever used full Photoshop – back to version 2.0! (Those were the days!) Layers appeared only with PS4 (I think) and that was wonderful.

But if you have Affinity Photo that has all the tricks. (But like PS, AP takes a bit of learning.)

Useful information from Les. I use Libre Office but have never explored it to that extent.

[Terry_VK5TM]

On the equipment to do the job, just purchased an Epson WorkForce DS-530II scanner.

Specs say max scan size is 8.5 x 240 inches (20 feet). Not going to be much use for anything wider (longer?) than the long edge of an A4 sheet, but would be interesting to see how it performs on something that will fit.

Didn't particularly buy it for the scan size, my current flatbed has started generating dead pixels in the scan head, leaving a coloured line on any scans.