Re: Retrieve the sub-type of a PDF file

My program opens a PDF file that has images that may or may not be compressed, for example TIFF with CCITT Group 4.

I can save the PDF with the compression I want.
But when I open the PDF, I can not know what was the compression used when saving.

Regardless of how the PDF was saved, the property in my case is RasPdfJpeg411 (152), but always returns RasPdf (146).

The version I'm using the LeadTools 16.5.

LEADTOOLS will load each page of the image as one RasterImage object, converting all text, bitmaps and drawing objects in that page to a single image during loading.
Therefore, LEADTOOLS will always treat the PDF page as a full-color image and will return the information of the PDF as 24-bit RasPdf file. If the page happened to contain a bitmap of a certain pixel depth or compression, there is no way of getting information about individual images or objects in the page.

Hello, we added support for this recently with CodecsRasterPdfInfo and RasterCodecs.GetRasterPdfInfo.

Make sure you have the latest version of Leadtools.Codecs.dll: At least 16.5.5.22 or 17.0.0.9.

This example code is straight out of the documentation. It creates a multi-page PDF with several bits/pixel and compression value, then uses the above methods/classes to split the PDF into multiple single page files with original bits/pixel, resolution, size and compression.

private static void CodecsRasterPdfInfoExample()
{
string multiPageRasterPdfFileName = @"C:\Users\Public\Documents\LEADTOOLS Images\MultiPageRasterPdf.pdf";
string pagesPdfFileNames = @"C:\Users\Public\Documents\LEADTOOLS Images\Page{0}.pdf";
// Create a 4 pages PDF file
CreateMultiPageRasterPdfFile(multiPageRasterPdfFileName);

// Without prior information, we will split this multi-page PDF file into
// multiple single page PDF files with original size, resolution, bit-depth and compression
using(RasterCodecs codecs = new RasterCodecs())
{
// Enable using our own resolution when loading PDF files
codecs.Options.RasterizeDocument.Load.Enabled = true;

int pagesSaved = 0;

// Get the file information
using(CodecsImageInfo imageInfo = codecs.GetInformation(multiPageRasterPdfFileName, true))
{
Console.WriteLine(
"Information: Format:\n Format: {0}\n Pages: {1}\n Bits/Pixel: {2}\n Size: {3} by {4}\n Resolution: {5} by {6}",
imageInfo.Format, imageInfo.TotalPages, imageInfo.BitsPerPixel, imageInfo.Width, imageInfo.Height, imageInfo.XResolution, imageInfo.YResolution);
Console.WriteLine("-----------------------");

// Now show the PDF specific information
// Notice: GetInformation will return RasPdf as the format for all PDF files
// regardless of the actual compression
if(imageInfo.Format == RasterImageFormat.RasPdf)
{
Console.WriteLine("Image is PDF, getting the specific info for each page");

for(int i = 0; i < imageInfo.TotalPages; i++)
{
int pageNumber = i + 1;

CodecsRasterPdfInfo pdfInfo = codecs.GetRasterPdfInfo(multiPageRasterPdfFileName, i + 1);
if(pageNumber == 1)
{
Console.WriteLine(" LEAD PDF?: {0}", pdfInfo.IsLeadPdf);
Console.WriteLine(" Version: {0}", pdfInfo.Version);
}

if(pdfInfo.IsLeadPdf)
{
Console.WriteLine(
"Page {0} of {1} info:\n Bits/Pixel: {2}\n Size: {3} by {4}\n Resolution: {5} by {6}\n Format: {7}",
pageNumber, imageInfo.TotalPages, pdfInfo.BitsPerPixel, pdfInfo.Width, pdfInfo.Height, pdfInfo.XResolution, pdfInfo.YResolution, pdfInfo.Format);
Console.WriteLine("-----------------------");

// Load this page with its original parameters
codecs.Options.RasterizeDocument.Load.XResolution = pdfInfo.XResolution;
codecs.Options.RasterizeDocument.Load.YResolution = pdfInfo.YResolution;
codecs.Options.Pdf.Load.DisplayDepth = pdfInfo.BitsPerPixel;

using(RasterImage pageImage = codecs.Load(multiPageRasterPdfFileName, 0, CodecsLoadByteOrder.BgrOrGray, pageNumber, pageNumber))
{
Console.WriteLine(
"Page {0} of {1} loaded:\n Bits/Pixel: {2}\n Size: {3} by {4}\n Resolution: {5} by {6}",
pageNumber, imageInfo.TotalPages, pageImage.BitsPerPixel, pageImage.Width, pageImage.Height, pageImage.XResolution, pageImage.YResolution);
Console.WriteLine("-----------------------");

// Setup the PDF save options
codecs.Options.Pdf.Save.UseImageResolution = true;
codecs.Options.Pdf.Save.Version = pdfInfo.Version;

// Save this page to a separate file
string pagePdfFileName = string.Format(pagesPdfFileNames, pageNumber);
codecs.Save(pageImage, pagePdfFileName, pdfInfo.Format, pdfInfo.BitsPerPixel);
pagesSaved++;
}
}
}
}
}

// We are done, now show the info of the generated files
for(int i = 0; i < pagesSaved; i++)
{
int pageNumber = i + 1;
string pagePdfFileName = string.Format(pagesPdfFileNames, pageNumber);

CodecsRasterPdfInfo pdfInfo = codecs.GetRasterPdfInfo(pagePdfFileName, 1);
Console.WriteLine(
"Page {0} of {1} info:\n Bits/Pixel: {2}\n Size: {3} by {4}\n Resolution: {5} by {6}\n Format: {7}",
pageNumber, pagesSaved, pdfInfo.BitsPerPixel, pdfInfo.Width, pdfInfo.Height, pdfInfo.XResolution, pdfInfo.YResolution, pdfInfo.Format);
Console.WriteLine("-----------------------");
}
}
}

private static void CreateMultiPageRasterPdfFile(string pdfFileName)
{
string sourceFile = @"C:\Users\Public\Documents\LEADTOOLS Images\Sample1.cmp";

// Delete the destination PDF file if exists
if(System.IO.File.Exists(pdfFileName))
{
System.IO.File.Delete(pdfFileName);
}

using(RasterCodecs codecs = new RasterCodecs())
{
// Save to PDF v1.4
codecs.Options.Pdf.Save.Version = CodecsRasterPdfVersion.V14;
// Save using image resolution
codecs.Options.Pdf.Save.UseImageResolution = true;

// Load the source file to use for each page
using(RasterImage pageImage = codecs.Load(sourceFile, 0, CodecsLoadByteOrder.BgrOrGray, 1, 1))
{
Console.WriteLine(
"Original image dimension:\n Size: {0} by {1}\n Resolution: {2} by {3}",
pageImage.Width, pageImage.Height, pageImage.XResolution, pageImage.YResolution);

// Array of bits/pixel and compression to use when saving the pages
int[] bitsPerPixel =
{
1,
8,
24
};
RasterImageFormat[] formats =
{
RasterImageFormat.RasPdfG4,
RasterImageFormat.RasPdfLzw,
RasterImageFormat.RasPdfJpeg422
};

int pageCount = bitsPerPixel.Length;
for(int i = 0; i < pageCount; i++)
{
// Append this page with given format
Console.WriteLine("Saving page {0} of {1} using {2} at {3}", i + 1, pageCount, bitsPerPixel[i], formats[i]);
codecs.Save(pageImage, pdfFileName, formats[i], bitsPerPixel[i], 1, 1, -1, CodecsSavePageMode.Append);
}
}

Console.WriteLine("-----------------------");
}
}