PDF Quality

Hi -

The quality of PDF documents displayed in the RasterImageViewer is poor compared to the Adobe Reader.

You can duplicate this issue by opening the attached PDF document with the LEADTOOLS Main Demo, and comparing it to the look of the document in the Adobe Reader.

I have tried adjusting codecs.Options.Pdf.Load.XResolution and codecs.Options.Pdf.Load.YResolution in the demo to higher values (as others have mentioned), but the quality remains poor.

Is there anything we can do to correct this issue?

Our version of LEAD is as follows:

Leadtools.dll - 17.0.0.19
Leadtools.codecs.dll - 17.0.0.22
Leadtools.codecs.Pdf.dll - 17.0.0.12
Leadtools.Pdf.dll - 17.0.0.3

Just saw the post about setting CodecsPdfLoadOptions.DisableCieColors to true.  Setting this property to true improves the quality of the image.

One other issue to note: the size (meaning amount of screen space occupied) of the PDF in the Main Demo is smaller than the size of the image in the Adobe Viewer.  Am I missing a setting somewhere?

What exactly do you mean by size of screen space? Do you mean the display zoom level? If yes, you can change that by setting the SizeMode property is RasterPaintSizeMode.Normal and changing the zoom factor using the ScaleFactor Property.
If you mean something else, please explain it in details.

When I open the image in the LEADTOOLS Main Demo with Size mode = Normal and Zoom = Normal (100%) (which I set through the demo menus), the displayed image is smaller than what Adobe shows me at Zoom = 100%.  The attached screen shots illustrate this issue.  The image in the adobe.jpg screenshot is wider and taller than the image in the mainDemo.jpg screenshot.

The concept of 100% is different from one application to the other when dealing with the same page on the same device.
Since the software does not really know how big or small your PC screen is (for example, it could be 4 inches or it could be 30 inches), there is no definite way to display an 8-inch page on the screen so that it will be exactly 8 inches.
The situation is different with printers, because you can query the printer and know what physical resolution it uses (such as 300 dots per inch or 600 DPI), and you can scale the image accordingly.

Should it matter what software displays the image on screen?  The image has the same number of pixels in it, and my monitor is set to the same resolution regardless of which piece of software prints the document.  Is there something else that goes into the calculation of how big to make the PDF on the screen other than the DPI, number of pixels in the image, and the relative display size - 100% in this case?

John,
I will explain below how we do the scaling exactly. As you will read, this is very well defined and predictable.
However, I cannot say how other non-LEAD applications perform their scaling, because that's outside the scope of our support.

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In LEADTOOLS, a certain zoom level such as 100% can be interpreted in 2 different ways:
1) If you disable the "Use DPI" feature, every pixel in the image is scaled according to screen pixels. Example A:
PDF is 8.5 inches wide.
When loading resolution is 100 DPI, for example, this produces an image that's 850 pixels wide.
Displaying at 100% causes the image width to be painted at 850 screen dots (1 image pixel => 1 screen pixel).

Example B:
Same PDF (8.5 inches wide)
When loading resolution is 200 DPI, this produces an image that's 1700 pixels wide.
Displaying at 100% causes the image width to be painted at 1700 screen dots (1 image pixel => 1 screen pixel).

2) If you enable the "Use DPI" feature, the screen resolution is also taken into account.
Example C (UseDPI = TRUE):
PDF is 8.5 inches wide.
When loading resolution is 100 DPI, this produces an image that's 850 pixels wide.
If the screen DPI is 96 (a very common value), every 96 dots on the screen are considered to be one inch.
Displaying at 100% causes the image width to be painted at 8.5 screen inches, which is equal to (8.5*96) = 816 dots (1 image INCH => 1 screen INCH).

Example D (UseDPI = TRUE):
Same PDF (8.5 inches wide)
When loading resolution is 200 DPI, this produces an image that's 1700 pixels wide.
If the screen DPI is also 96, every 96 dots on the screen are considered to be one inch.
Displaying at 100% causes the image width to be painted at 8.5 screen inches, which is equal to (8.5*96) = 816 dots (1 image INCH => 1 screen INCH).