private static bool optimizeImage(PdfPaintedImage painted)
{
PdfImage image = painted.Image;
// inline images can not be recompressed unless you move them to resources
// using PdfCanvas.MoveInlineImagesToResources
if (image.IsInline)
{
return(false);
}
// mask images are not good candidates for recompression
if (image.IsMask || image.Width < 8 || image.Height < 8)
{
return(false);
}
// get size of the painted image
int width = Math.Max(1, (int)painted.Bounds.Width);
int height = Math.Max(1, (int)painted.Bounds.Height);
// calculate resize ratio
double ratio = Math.Min(image.Width / (double)width, image.Height / (double)height);
if (ratio <= 1)
{
// the image size is smaller then the painted size
return(recompressImage(image));
}
if (ratio < 1.1)
{
// with ratio this small, the potential size reduction
// usually does not justify resizing artefacts
return(false);
}
if (image.Compression == PdfImageCompression.Group4Fax ||
image.Compression == PdfImageCompression.Group3Fax ||
image.Compression == PdfImageCompression.JBig2 ||
(image.ComponentCount == 1 && image.BitsPerComponent == 1))
{
return(resizeBilevelImage(image, ratio));
}
int resizedWidth = (int)Math.Floor(image.Width / ratio);
int resizedHeight = (int)Math.Floor(image.Height / ratio);
if ((image.ComponentCount >= 3 && image.BitsPerComponent == 8) || isGrayJpeg(image))
{
image.ResizeTo(resizedWidth, resizedHeight, PdfImageCompression.Jpeg, 90);
// or image.ResizeTo(resizedWidth, resizedHeight, PdfImageCompression.Jpeg2000, 10);
}
else
{
image.ResizeTo(resizedWidth, resizedHeight, PdfImageCompression.Flate, 9);
}
return(true);
}
private static bool resizeBilevelImage(PdfImage image, double ratio)
{
// Fax documents usually look better if integer-ratio scaling is used
// Fractional-ratio scaling introduces more artifacts
int intRatio = (int)ratio;
// decrease the ratio when it is too high
if (intRatio > 3)
{
intRatio = Math.Min(intRatio - 2, 3);
}
if (intRatio == 1 && image.Compression == PdfImageCompression.Group4Fax)
{
// skipping the image, because the output size and compression are the same
return(false);
}
image.ResizeTo(image.Width / intRatio, image.Height / intRatio, PdfImageCompression.Group4Fax);
return(true);
}
private static bool optimizeImage(PdfPaintedImage painted, PdfDocument pdf)
{
PdfImage image = painted.Image;
// inline images can not be recompressed unless you move them to resources
// using PdfCanvas.MoveInlineImagesToResources
if (image.IsInline)
{
return(false);
}
// mask images are not good candidates for recompression
if (image.IsMask || image.Width < 8 || image.Height < 8)
{
return(false);
}
// get size of the painted image
int width = Math.Max(1, (int)painted.Bounds.Width);
int height = Math.Max(1, (int)painted.Bounds.Height);
if (width >= image.Width || height >= image.Height)
{
if (image.HasMask)
{
return(false);
}
if (image.ComponentCount == 1 && image.BitsPerComponent == 1 &&
image.Compression != PdfImageCompression.Group4Fax)
{
image.RecompressWithGroup4Fax();
}
else if (image.BitsPerComponent == 8 &&
image.ComponentCount >= 3 &&
image.Compression != PdfImageCompression.Jpeg &&
image.Compression != PdfImageCompression.Jpeg2000)
{
image.RecompressWithJpeg2000(10);
// or image.RecompressWithJpeg();
}
return(true);
}
// try to replace large masked images
if (image.HasMask)
{
if (image.Width < 300 || image.Height < 300)
{
return(false);
}
using (var stream = new MemoryStream())
{
PdfPage tempPage = pdf.AddPage();
tempPage.Canvas.DrawImage(image, 0, 0, width, height, 0);
PdfPaintedImage tempPaintedImage = tempPage.GetPaintedImages()[0];
tempPaintedImage.SaveAsPainted(stream);
pdf.RemovePage(pdf.PageCount - 1);
image.ReplaceWith(stream);
return(true);
}
}
if (image.Compression == PdfImageCompression.Group4Fax ||
image.Compression == PdfImageCompression.Group3Fax)
{
// Fax documents usually looks better if integer-ratio scaling is used
// Fractional-ratio scaling introduces more artifacts
int ratio = Math.Min(image.Width / width, image.Height / height);
// decrease the ratio when it is too high
if (ratio > 6)
{
ratio -= 5;
}
else if (ratio > 3)
{
ratio -= 2;
}
image.ResizeTo(image.Width / ratio, image.Height / ratio, PdfImageCompression.Group4Fax);
}
else if (image.ComponentCount >= 3 && image.BitsPerComponent == 8)
{
image.ResizeTo(width, height, PdfImageCompression.Jpeg, 90);
}
else
{
image.ResizeTo(width, height, PdfImageCompression.Flate, 9);
}
return(true);
}
public static void Main()
{
// NOTE:
// When used in trial mode, the library imposes some restrictions.
// Please visit http://bitmiracle.com/pdf-library/trial-restrictions.aspx
// for more information.
const string originalFile = @"Sample Data\jpeg.pdf";
const string compressedFile = "CompressAllTechniques.pdf";
using (var pdf = new PdfDocument(originalFile))
{
// 1. Recompress images
foreach (PdfPage page in pdf.Pages)
{
foreach (PdfPaintedImage painted in page.GetPaintedImages())
{
PdfImage image = painted.Image;
// image that is used as mask or image with attached mask are
// not good candidates for recompression
if (image.IsMask || image.Mask != null || image.Width < 8 || image.Height < 8)
{
continue;
}
// get size of the painted image
int width = Math.Max(1, (int)painted.Bounds.Width);
int height = Math.Max(1, (int)painted.Bounds.Height);
if (width >= image.Width || height >= image.Height)
{
if (image.ComponentCount == 1 && image.BitsPerComponent == 1 &&
image.Compression != PdfImageCompression.Group4Fax)
{
image.RecompressWithGroup4Fax();
}
else if (image.BitsPerComponent == 8 &&
image.ComponentCount >= 3 &&
image.Compression != PdfImageCompression.Jpeg &&
image.Compression != PdfImageCompression.Jpeg2000)
{
image.RecompressWithJpeg2000(10);
// or image.RecompressWithJpeg();
}
}
else
{
// NOTE: PdfImage.ResizeTo() method is not supported in version for .NET Standard
if (image.Compression == PdfImageCompression.Group4Fax ||
image.Compression == PdfImageCompression.Group3Fax)
{
// Fax documents usually looks better if integer-ratio scaling is used
// Fractional-ratio scaling introduces more artifacts
int ratio = Math.Min(image.Width / width, image.Height / height);
image.ResizeTo(image.Width / ratio, image.Height / ratio, PdfImageCompression.Group4Fax);
}
else if (image.ComponentCount >= 3 && image.BitsPerComponent == 8)
{
image.ResizeTo(width, height, PdfImageCompression.Jpeg, 90);
}
else
{
image.ResizeTo(width, height, PdfImageCompression.Flate, 9);
}
}
}
}
// 2 Setup save options
pdf.SaveOptions.Compression = PdfCompression.Flate;
pdf.SaveOptions.UseObjectStreams = true;
pdf.SaveOptions.RemoveUnusedObjects = true;
pdf.SaveOptions.OptimizeIndirectObjects = true;
pdf.SaveOptions.WriteWithoutFormatting = true;
// 3. Remove structure information
pdf.RemoveStructureInformation();
// 4. Flatten form fields
// Controls become uneditable after that
pdf.FlattenControls();
// 5. Clear metadata
pdf.Metadata.Basic.Clear();
pdf.Metadata.DublinCore.Clear();
pdf.Metadata.MediaManagement.Clear();
pdf.Metadata.Pdf.Clear();
pdf.Metadata.RightsManagement.Clear();
pdf.Metadata.Custom.Properties.Clear();
foreach (XmpSchema schema in pdf.Metadata.Schemas)
{
schema.Properties.Clear();
}
pdf.Info.Clear(false);
// 6. Remove font duplicates
pdf.ReplaceDuplicateFonts();
// 7. Unembed fonts
foreach (PdfFont font in pdf.GetFonts())
{
// Only unembed popular fonts installed in the typical OS. You can extend
// the list of such fonts in the "if" statement below.
if (font.Name == "Arial" || font.Name == "Verdana")
{
font.Unembed();
}
}
pdf.Save(compressedFile);
}
string message = string.Format(
"Original file size: {0} bytes;\r\nCompressed file size: {1} bytes",
new FileInfo(originalFile).Length,
new FileInfo(compressedFile).Length
);
MessageBox.Show(message);
Process.Start(compressedFile);
}
public static void Main()
{
// NOTE:
// When used in trial mode, the library imposes some restrictions.
// Please visit http://bitmiracle.com/pdf-library/trial-restrictions.aspx
// for more information.
const string originalFile = @"Sample Data\jpeg.pdf";
const string compressedFile = "OptimizeImages.pdf";
using (PdfDocument pdf = new PdfDocument(originalFile))
{
foreach (PdfPage page in pdf.Pages)
{
foreach (PdfPaintedImage painted in page.GetPaintedImages())
{
PdfImage image = painted.Image;
// inline images can not be recompressed unless you move them to resources
// using PdfCanvas.MoveInlineImagesToResources
if (image.IsInline)
{
continue;
}
// image that is used as mask or image with attached mask are
// not good candidates for recompression
if (image.IsMask || image.Mask != null || image.Width < 8 || image.Height < 8)
{
continue;
}
// get size of the painted image
int width = Math.Max(1, (int)painted.Bounds.Width);
int height = Math.Max(1, (int)painted.Bounds.Height);
if (width >= image.Width || height >= image.Height)
{
if (image.ComponentCount == 1 && image.BitsPerComponent == 1 &&
image.Compression != PdfImageCompression.Group4Fax)
{
image.RecompressWithGroup4Fax();
}
else if (image.BitsPerComponent == 8 &&
image.ComponentCount >= 3 &&
image.Compression != PdfImageCompression.Jpeg &&
image.Compression != PdfImageCompression.Jpeg2000)
{
image.RecompressWithJpeg2000(10);
// or image.RecompressWithJpeg();
}
}
else
{
if (image.Compression == PdfImageCompression.Group4Fax ||
image.Compression == PdfImageCompression.Group3Fax)
{
// Fax documents usually looks better if integer-ratio scaling is used
// Fractional-ratio scaling introduces more artifacts
int ratio = Math.Min(image.Width / width, image.Height / height);
image.ResizeTo(image.Width / ratio, image.Height / ratio, PdfImageCompression.Group4Fax);
}
else if (image.ComponentCount >= 3 && image.BitsPerComponent == 8)
{
image.ResizeTo(width, height, PdfImageCompression.Jpeg, 90);
}
else
{
image.ResizeTo(width, height, PdfImageCompression.Flate, 9);
}
}
}
}
pdf.Save(compressedFile);
}
string message = string.Format(
"Original file size: {0} bytes;\r\nCompressed file size: {1} bytes",
new FileInfo(originalFile).Length,
new FileInfo(compressedFile).Length
);
MessageBox.Show(message);
Process.Start(compressedFile);
}