Just found these, might be of interest to some here


http://www.keith-snook.info/wireless...ireless-world-
articles.html
--
Tony Sayer

In article , tony sayer

wrote:


Just found these, might be of interest to some here


http://www.keith-snook.info/wireless...ireless-world-
articles.html

They are! Alas, the first one I tried showed my some of the irritating
problems that get in the way of using such files as reliable scans of
original pages.

I tried various pdf software. The pages seem to be 'patchwork quilt'
reconstructions. This means it is almost impossible to know what rendering
dpi (if any!) would give a result which had no added degrading due to
rendering. And also gives no clue if the 'processing' done to clean up the
scan for getting a 'better' pdf by the creator has actually altered any
real details.

I realise some rendering / processing software does this to try and cut
down file size and 'look better'. But for archival/research purposes it
undermines confidence.

However the content is certainly interesting. And tends to look better than
the examples on the americanradiohistory site.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

"Jim Lesurf" wrote in message
...
In article , tony sayer

wrote:


Just found these, might be of interest to some here


http://www.keith-snook.info/wireless...ireless-world-
articles.html

They are! Alas, the first one I tried showed my some of the irritating
problems that get in the way of using such files as reliable scans of
original pages.

I tried various pdf software. The pages seem to be 'patchwork quilt'
reconstructions. This means it is almost impossible to know what rendering
dpi (if any!) would give a result which had no added degrading due to
rendering. And also gives no clue if the 'processing' done to clean up the
scan for getting a 'better' pdf by the creator has actually altered any
real details.

I realise some rendering / processing software does this to try and cut
down file size and 'look better'. But for archival/research purposes it
undermines confidence.

However the content is certainly interesting. And tends to look better
than
the examples on the americanradiohistory site.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics
http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

I picked one at random (Micro-controlled radio-code clock) and thought he
has done an excellent job for most interested parties. Scan looks good and
even has accurate OCR of the text I checked.

On 04/12/2016 12:29, MikeS wrote:
"Jim Lesurf" wrote in message
...
In article , tony sayer

wrote:


Just found these, might be of interest to some here


Agreed, thanks!


http://www.keith-snook.info/wireless...ireless-world-
articles.html

They are! Alas, the first one I tried showed my some of the irritating
problems that get in the way of using such files as reliable scans of
original pages.

I tried various pdf software. The pages seem to be 'patchwork quilt'
reconstructions. This means it is almost impossible to know what rendering
dpi (if any!) would give a result which had no added degrading due to
rendering. And also gives no clue if the 'processing' done to clean up the
scan for getting a 'better' pdf by the creator has actually altered any
real details.


Not sure why you'd want to know, but:

PDF producer: Adobe Acrobat 9.55 Paper Capture Plug-in with ClearScan
Content creator: Adobe Acrobat 9.5.5

for the couple I looked at.

I realise some rendering / processing software does this to try and cut
down file size and 'look better'. But for archival/research purposes it
undermines confidence.


I've a bunch of old journals I need to scan. I was just going to use
'compact pdf' on the work copier. It gives a reasonable rendition,
perfectly legible, with decent file sizes. Is there some sort of
industry standard (that I clearly don't know about)?

However the content is certainly interesting. And tends to look better
than
the examples on the americanradiohistory site.

I picked one at random (Micro-controlled radio-code clock) and thought he
has done an excellent job for most interested parties. Scan looks good and
even has accurate OCR of the text I checked.


I'd agree. To the point that I don't think they are scans - at least the
ones I looked at. I'm sent print proofs for some editing that I do, and
they look to be of that order of quality. Maybe Jim's looking at a
couple of rogue examples?

--
Cheers, Rob

In article , RJH
wrote:

I'd agree. To the point that I don't think they are scans - at least the
ones I looked at. I'm sent print proofs for some editing that I do, and
they look to be of that order of quality. Maybe Jim's looking at a
couple of rogue examples?

I looked at the earliest. This is a patchwork of bitmaps and overlaid OCR'd
text. I used pdfutils like pdfimages to examine the contents. The patchwork
images are jpegs.

So what you see with a PDF rendering program will depend on the rendering.

I guess this may vary from one of the files to another.

The main problem for future historians and academics is how to *know* the
results are always perfectly accurate when they may have no access to an
original or a plain scan. If they need to refer to a more 'reliable'
version then they may as well use that!

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

On 04 Dec, wrote:

I looked at the earliest. This is a patchwork of bitmaps and overlaid
OCR'd text. I used pdfutils like pdfimages to examine the contents. The
patchwork images are jpegs.

In case anyone is interested, here is the start of the info for the April
1939 file on Keith's WW scans page. I've just listed the first 3 pages so
you can see the details of the contained patchwork of bitmaps. (This
utility ignores OCR'd text).

pdfimages -list Phase-Splitting_in_Push-Pull_Amplifiers.pdf
page num type width height color comp bpc enc interp object ID x-ppi
y-ppi size ratio
--------------------------------------------------------------------------------------------
1 0 image 589 828 gray 1 8 jpeg no 248 0 72
73 326B 0.1%
1 1 image 1140 1040 gray 1 8 jpeg no 249 0 300
300 63.8K 5.5%
1 2 image 736 12 gray 1 8 jpeg no 250 0 301
300 1965B 22%
1 3 image 728 992 gray 1 8 jpeg no 251 0 300
300 39.3K 5.6%
1 4 image 736 16 gray 1 8 jpeg no 252 0 301
301 2545B 22%
1 5 stencil 8 6 - 1 1 image no [inline] 600
600 - -
2 6 image 586 825 gray 1 8 jpeg no 235 0 73
72 383B 0.1%
2 7 image 996 988 gray 1 8 jpeg no 236 0 301
301 204K 21%
2 8 image 1144 796 gray 1 8 jpeg no 237 0 300
301 49.7K 5.6%
2 9 image 728 988 gray 1 8 jpeg no 238 0 300
301 35.5K 5.1%
2 10 image 1764 62 gray 1 8 jpeg no 239 0 601
600 10.1K 9.5%
2 11 image 86 49 gray 1 8 jpeg no 240 0 600
600 1643B 39%
3 12 image 586 825 gray 1 8 jpeg no 221 0 72
73 362B 0.1%
3 13 image 296 104 gray 1 8 jpeg no 222 0 300
306 8696B 28%
3 14 image 60 36 gray 1 8 jpeg no 223 0 299
304 1230B 57%
3 15 image 1132 768 gray 1 8 jpeg no 224 0 299
303 53.1K 6.3%
3 16 image 100 8 gray 1 8 jpeg no 225 0 300
327 377B 47%
3 17 image 1156 768 gray 1 8 jpeg no 226 0 299
304 57.0K 6.6%
3 18 image 752 20 gray 1 8 jpeg no 227 0 300
400 2356B 16%
3 19 image 1565 50 gray 1 8 jpeg no 228 0 600
757 7431B 9.5%

etc

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

On 04/12/2016 15:51, Jim Lesurf wrote:
In article , RJH
wrote:

I'd agree. To the point that I don't think they are scans - at least the
ones I looked at. I'm sent print proofs for some editing that I do, and
they look to be of that order of quality. Maybe Jim's looking at a
couple of rogue examples?

I looked at the earliest. This is a patchwork of bitmaps and overlaid OCR'd
text. I used pdfutils like pdfimages to examine the contents. The patchwork
images are jpegs.


I think the result looks very tidy in the 2 readers I have on my Mac -
Preview and Adobe Acrobat Reader.

Looking at it more closely, though, I'd agree that it is an odd example.
The image files copy and paste very neatly. I'm used to 'snipping' pdf
extracts for use elsewhere. And all text is readily selectable.

So what you see with a PDF rendering program will depend on the rendering.


Do you mean a PDF reader? Yes, that's likely - I often see slight
differences in pdfs, depending on the reader.

I guess this may vary from one of the files to another.

The main problem for future historians and academics is how to *know* the
results are always perfectly accurate when they may have no access to an
original or a plain scan. If they need to refer to a more 'reliable'
version then they may as well use that!


Yes, I see what you mean now. Can't say it would have occurred to me to
be *that* important! But of course libraries and so on would need some
form of standard.

Is there a preferred method of archiving documents to pdf? I'd assume
it'd be a page-to-image type arrangement? A quick search shows PDF/A:

https://www.pdfa.org/pdfa-faq/

And from there, Adobe Acrobat appears to offer the option.

Wonder why Keith saved them in that way?


--
Cheers, Rob

In article , RJH
wrote:
The main problem for future historians and academics is how to *know*
the results are always perfectly accurate when they may have no access
to an original or a plain scan. If they need to refer to a more
'reliable' version then they may as well use that!


Yes, I see what you mean now. Can't say it would have occurred to me to
be *that* important! But of course libraries and so on would need some
form of standard.

Is there a preferred method of archiving documents to pdf? I'd assume
it'd be a page-to-image type arrangement? A quick search shows PDF/A:

https://www.pdfa.org/pdfa-faq/

And from there, Adobe Acrobat appears to offer the option.

The problem being that this may not be something someone 100 years from now
may have to hand. And the more layers of tweaking there are, the more ways
to get mistakes or problems there will be.

So PDF isn't 'preferred' at all. Although, as will millions of Word docs,
future historians may have to struggle with them when MicroSoft have long
gone.

Wonder why Keith saved them in that way?

I've exchanged a couple of emails with him about this. I think he felt this
was the best way to minimise file size whilst keeping visual quality.
Certainly OCR is useful for that. Problem is that this makes a number of
implicity assumptions about what rendering software people are using, etc.
Which may not be so for the far future.

Indeed, he said to me he scans at 600 dpi and doesn't use jpegs. But the
patchwork images in the file I looked at *are* jpegs, and not all 600 dpi.
I'm not sure yet if he knows that his PDF software may be doing that
without him realising.

Simple example of potential causes of problems. When rendered on-screen the
tendency for many OS is to assume a base of 72dpi. Yet the main OS I use a
lot of the time is based on 90 dpi. So the same 'size' of image on-screen
calculated in terms of a paper size specified by a PDF in inches (or mm)
may look better on one machine than the other. Then consider rips or
renderers for paper. There you'd have to rely on an lpi that is large
enough to ensure this won't matter.

What dpi will screens on devices 100 years from now be based upon? Seems
doubtful it will be as low as 72 or 90. But who knows (yet)?

Hence even if a PDF 'optimally' scales things for reading, that
'optimisation' includes some assumptions that may be false. And some PDFs I
see have no dpi values for some images.

Hence the simplest approach is to keep to plain bitmaps with a specificed
dpi. One bitmap per page/scan. This removes all the added 'clever'
processes that give more ways to slip up.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

"Jim Lesurf" wrote in message
...
In article , RJH
wrote:
The main problem for future historians and academics is how to *know*
the results are always perfectly accurate when they may have no access
to an original or a plain scan. If they need to refer to a more
'reliable' version then they may as well use that!


Yes, I see what you mean now. Can't say it would have occurred to me to
be *that* important! But of course libraries and so on would need some
form of standard.

Is there a preferred method of archiving documents to pdf? I'd assume
it'd be a page-to-image type arrangement? A quick search shows PDF/A:

https://www.pdfa.org/pdfa-faq/

And from there, Adobe Acrobat appears to offer the option.

The problem being that this may not be something someone 100 years from
now
may have to hand. And the more layers of tweaking there are, the more ways
to get mistakes or problems there will be.

So PDF isn't 'preferred' at all. Although, as will millions of Word docs,
future historians may have to struggle with them when MicroSoft have long
gone.

Wonder why Keith saved them in that way?

I've exchanged a couple of emails with him about this. I think he felt
this
was the best way to minimise file size whilst keeping visual quality.
Certainly OCR is useful for that. Problem is that this makes a number of
implicity assumptions about what rendering software people are using, etc.
Which may not be so for the far future.

Indeed, he said to me he scans at 600 dpi and doesn't use jpegs. But the
patchwork images in the file I looked at *are* jpegs, and not all 600 dpi.
I'm not sure yet if he knows that his PDF software may be doing that
without him realising.

Simple example of potential causes of problems. When rendered on-screen
the
tendency for many OS is to assume a base of 72dpi. Yet the main OS I use a
lot of the time is based on 90 dpi. So the same 'size' of image on-screen
calculated in terms of a paper size specified by a PDF in inches (or mm)
may look better on one machine than the other. Then consider rips or
renderers for paper. There you'd have to rely on an lpi that is large
enough to ensure this won't matter.

What dpi will screens on devices 100 years from now be based upon? Seems
doubtful it will be as low as 72 or 90. But who knows (yet)?

Hence even if a PDF 'optimally' scales things for reading, that
'optimisation' includes some assumptions that may be false. And some PDFs
I
see have no dpi values for some images.

Hence the simplest approach is to keep to plain bitmaps with a specificed
dpi. One bitmap per page/scan. This removes all the added 'clever'
processes that give more ways to slip up.

Jim

I think you have to distinguish between amateurs putting past printed
material online in a format suitable for interested readers to enjoy and
professionals creating long term historical archives. The Bristish Museum
has Wireless World in its collection and no doubt will get around to a
digital archive before the paper deteriorates too far. That will use
something like JPEG2000 which would not be very convenient for direct use by
a casual reader wanting to download and browse the magazine.

In article , MikeS
wrote:
I think you have to distinguish between amateurs putting past printed
material online in a format suitable for interested readers to enjoy and
professionals creating long term historical archives.

Yes, I'd agree. I can see why PDF is very convenient as things stand for
many people. More so than a set of 'one file per page' with larger file
sizes. Similarly, for various current 'e-books' formats.

FWIW UKHHSoc do use and accept PDFs, even ones that have the problems.
You'll find examples on the public site. Simply because having access to
the information content is much better than *not* having it. But as soon as
archiving for the future is concerned, the kinds of points I made begin to
be things we need to consider. So they are something I worry about and try
to alert people to take into account.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html