Flatten comments - bug

[BobM]

When a pdf has an image pasted into it, the image can fixed in place using the "flatten comments" option.
However, doing this on a large file causes the content underneath the image to be momentarily displayed when zooming in and out, probably due to the low refresh speed on the screen.
Whilst irritating in PDF-XChange Viewer, it is particularly annoying in Acrobat which suffers the problem on relatively small files.
The attachment contains a pdf illustrating the problem (see the table at the top right when zooming). Unfortunately, the obvious workaround, printing the file using a pdf driver, produces its own problems:
1. Using CutePdf/PDF995 drivers creates a pdf that contains horizontal line artefacts when viewed on screen.
2. Using Acrobat Distiller creates a smaller file but doesn't make the pasted image part of the pdf, so it still flickers.
An alternative option is to export the flattened file to a PNG image, but that results in a 7 MB file (from an 800KB original). However, using this method, there is no way of creating a pdf from the PNG using PDF Xchange Viewer alone.

Note: The "Add a file" option is currently failing with a "This webpage is not available" error, but the file is temporarily available here: https://www.sizablesend.com/file/f1r87k/19331.7z

[Stefan - PDF-XChange]

Hello Bob,

Flattening comments makes them permanent part of the document but does not "erase" the underlying content, or "merge" the new image with an existing one below. So while a flattened comment is now permanent part of the "base" PDF it is still a separate object, and rendered independently - hence the option for you to see what is below for a fraction of a second.

As for exporting and then importing back - it is possible with the Viewer Alone - there is the File -> New Document -> From Image files... option.

Best,
Stefan

[BobM]

Thanks Stefan - that seems to work.
Is there any reason the png image (from the 800 KB pdf) produced by PDF-XChange is 7.5 MB whilst that from Acrobat is only 2.2 MB? (Both are set to 300 dpi).

[Stefan - PDF-XChange]

Hello Bob,

I managed to get the file down to 3.4 Mb with using Grayscale - maybe Adobe are auto detecting that your file is already "colourless" and are silently setting the PNG to grayscale - I can not test that as I don't have a license for their products, and the free Reader does not allow me to export to image.

In order to access the properties, when you have selected "File -> Export -> Export to image..."
next to the file format drop down there is an "Options..." button - which will present you with the options for exporting to the currently selected file format.

I also checked and the image that is the base of your file is with a resolution of 72 DPI, so exporting to 300 dpi will not improve the quality.

Best,
Stefan

[BobM]

Stefan,

(Old thread, I know, but I'm still having issues with the huge images PDF Xchange is producing).

I'd be interested to know how you are able to determine the resolution of the image that is the base of the file?
When "exporting to image", the options box for the image type only displays the same DPI setting that is shown at the bottom of the Export to image dialogue box.
If the image really was only 72 DPI, that would account for the large difference in file size between the PDF (@72 DPI internally) and the PNG (@ 300 DPI).

Am I missing something?

Bob

PS Original PDF reattached
PPS Your forum software doesn't inform the uploader that his large file exceeds the size limit until after the upload has completed and failed. It would be better to understand the limit before starting.

[Stefan - PDF-XChange]

Hello Bob,

Apologies - I might have been rather wrong the first time.
The originally scanned document is with a 400 DPI resolution.
18724 x 13244 Pixels on a 46.81 x 33.11 inch sheet.

This time I extracted the images using PDF-Tools and then opened them with an image editing software to get the dimensions.

It still seems like Adobe have made some auto detection and reduced the amount of colours used in the PNG they created as when I tried with black and white only through our Viewer - the result is 1.15 MB PNG, and this is acceptable as the original is in fact a black and white image, so no loss is occurring from the selection of colour range.

And still the best result I could achieve was to archive the .bmp extracted from the file - the result was 799Kb (out of a 29.6 Mb image).

p.s. Actually when I exported the bmp from the changed document - the result was 1.01 Mb Archive of a 16.6 Mb bmp (002.rar)

Best,
Stefan