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Convert PDF to image (JPG, PNG, BMP, TIFF) in Ruby

Sample Ruby code to use PDFTron SDK's built-in rasterizer to render PDF images on the fly and save the resulting images in various raster image formats (such as PNG, JPEG, BMP, TIFF). Learn more about our PDF Conversion Library.

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#---------------------------------------------------------------------------------------
# Copyright (c) 2001-2019 by PDFTron Systems Inc. All Rights Reserved.
# Consult LICENSE.txt regarding license information.
#---------------------------------------------------------------------------------------

require '../../../PDFNetC/Lib/PDFNetRuby'
include PDFNetRuby

$stdout.sync = true

# Relative path to the folder containing test files.
input_path =  "../../TestFiles/"
output_path = "../../TestFiles/Output/"

#---------------------------------------------------------------------------------------
# The following sample illustrates how to convert PDF documents to various raster image 
# formats (such as PNG, JPEG, BMP, TIFF, etc), as well as how to convert a PDF page to 
# GDI+ Bitmap for further manipulation and/or display in WinForms applications.
#---------------------------------------------------------------------------------------

	# The first step in every application using PDFNet is to initialize the 
	# library and set the path to common PDF resources. The library is usually 
	# initialized only once, but calling Initialize multiple times is also fine.
	PDFNet.Initialize
	
	# Optional: Set ICC color profiles to fine tune color conversion 
	# for PDF 'device' color spaces...

	# PDFNet.SetResourcesPath("../../../resources")
	# PDFNet.SetColorManagement
	# PDFNet.SetDefaultDeviceCMYKProfile("D:/Misc/ICC/USWebCoatedSWOP.icc")
	# PDFNet.SetDefaultDeviceRGBProfile("AdobeRGB1998.icc") # will search in PDFNet resource folder.

	# ----------------------------------------------------
	# Optional: Set predefined font mappings to override default font 
	# substitution for documents with missing fonts...

	# PDFNet.AddFontSubst("StoneSans-Semibold", "C:/WINDOWS/Fonts/comic.ttf")
	# PDFNet.AddFontSubst("StoneSans", "comic.ttf")  # search for 'comic.ttf' in PDFNet resource folder.
	# PDFNet.AddFontSubst(PDFNet.E_Identity, "C:/WINDOWS/Fonts/arialuni.ttf")
	# PDFNet.AddFontSubst(PDFNet.E_Japan1, "C:/Program Files/Adobe/Acrobat 7.0/Resource/CIDFont/KozMinProVI-Regular.otf")
	# PDFNet.AddFontSubst(PDFNet.E_Japan2, "c:/myfonts/KozMinProVI-Regular.otf")
	# PDFNet.AddFontSubst(PDFNet.E_Korea1, "AdobeMyungjoStd-Medium.otf")
	# PDFNet.AddFontSubst(PDFNet.E_CNS1, "AdobeSongStd-Light.otf")
	# PDFNet.AddFontSubst(PDFNet.E_GB1, "AdobeMingStd-Light.otf")
	
	#Example 1) Convert the first page to PNG and TIFF at 92 DPI.
	
	# PDFDraw class is used to rasterize PDF pages.
	draw = PDFDraw.new
	
	#--------------------------------------------------------------------------------
	# Example 1) Convert the first page to PNG and TIFF at 92 DPI. 
	# A three step tutorial to convert PDF page to an image.
	
	# A) Open the PDF document.
	doc = PDFDoc.new(input_path + "tiger.pdf")
	
	# Initialize the security handler, in case the PDF is encrypted.
	doc.InitSecurityHandler
	
	# B) The output resolution is set to 92 DPI.
	draw.SetDPI(92)
	
	# C) Rasterize the first page in the document and save the result as PNG.
	itr = doc.GetPageIterator
	draw.Export(itr.Current, output_path + "tiger_92dpi.png")
	
	puts "Example 1: tiger_92dpi.png"
	
	# Export the same page as TIFF
	itr = doc.GetPageIterator
	draw.Export(itr.Current, (output_path + "tiger_92dpi.tif"), "TIFF")
	
	#--------------------------------------------------------------------------------
	# Example 2) Convert the all pages in a given document to JPEG at 72 DPI.

	puts "Example 2:"
	
	hint_set = ObjSet.new # A collection of rendering 'hits'.
	
	doc = PDFDoc.new(input_path + "newsletter.pdf")
	# Initialize the security handler, in case the PDF is encrypted.
	doc.InitSecurityHandler
	
	# Set the output resolution is to 72 DPI.
	draw.SetDPI(72)
	
	# Use optional encoder parameter to specify JPEG quality.
	encoder_param = hint_set.CreateDict
	encoder_param.PutNumber("Quality", 80)
	
	# Traverse all pages in the document.
	itr = doc.GetPageIterator
	while itr.HasNext do
		filename = "newsletter" + itr.Current.GetIndex.to_s + ".jpg"
		puts filename
		draw.Export(itr.Current, output_path + filename, "JPEG", encoder_param)
		itr.Next
	end
	puts "Done."

	# Examples 3-5
	# Common code for remaining samples.
	tiger_doc = PDFDoc.new(input_path + "tiger.pdf")
	# Initialize the security handler, in case the PDF is encrypted.
	tiger_doc.InitSecurityHandler
	page = tiger_doc.GetPage(1)
	
	#--------------------------------------------------------------------------------
	# Example 3) Convert the first page to raw bitmap. Also, rotate the 
	# page 90 degrees and save the result as RAW.
	draw.SetDPI(100)	# Set the output resolution is to 100 DPI.
	draw.SetRotate(Page::E_90)   # Rotate all pages 90 degrees clockwise.
	bmp = draw.GetBitmap(page, PDFDraw::E_rgb)

	# Save the raw RGB data to disk.
	File.open(output_path + "tiger_100dpi_rot90.raw", 'w') { |file| file.write(bmp.GetBuffer) }
	
	puts "Example 3: tiger_100dpi_rot90.raw"
	
	draw.SetRotate(Page::E_0)	# Disable image rotation for remaining samples.
	
	#--------------------------------------------------------------------------------
	# Example 4) Convert PDF page to a fixed image size. Also illustrates some 
	# other features in PDFDraw class such as rotation, image stretching, exporting 
	# to grayscale, or monochrome.
	
	# Initialize render 'gray_hint' parameter, that is used to control the 
	# rendering process. In this case we tell the rasterizer to export the image as 
	# 1 Bit Per Component (BPC) image.
	mono_hint = hint_set.CreateDict
	mono_hint.PutNumber("BPC", 1)
	
	# SetImageSize can be used instead of SetDPI to adjust page scaling
	# dynamically so that given image fits into a buffer of given dimensions.
	draw.SetImageSize(1000, 1000)   # Set the output image to be 1000 wide and 1000 pixels tall
	draw.Export(page, output_path + "tiger_1000x1000.png", "PNG", mono_hint)
	puts "Example 4: tiger_1000x1000.png"
	
	draw.SetImageSize(200, 400)	 # Set the output image to be 200 wide and 400 pixels tall
	draw.SetRotate(Page::E_180)	 # Rotate all pages 90 degrees clockwise
	
	# 'gray_hint' tells the rasterizer to export the image as grayscale.
	gray_hint = hint_set.CreateDict
	gray_hint.PutName("ColorSpace", "Gray")
	
	draw.Export(page, (output_path + "tiger_200x400_rot180.png"), "PNG", gray_hint)
	puts "Example 4: tiger_200x400_rot180.png"
	
	draw.SetImageSize(400, 200, false)  # The third parameter sets 'preserve-aspect-ratio' to false
	draw.SetRotate(Page::E_0)	 # Disable image rotation
	draw.Export(page, output_path + "tiger_400x200_stretch.jpg", "JPEG")
	puts "Example 4: tiger_400x200_stretch.jpg"
	
	#--------------------------------------------------------------------------------
	# Example 5) Zoom into a specific region of the page and rasterize the 
	# area at 200 DPI and as a thumbnail (i.e. a 50x50 pixel image).
	zoom_rect = Rect.new(216, 522, 330, 600)
	page.SetCropBox(zoom_rect)	# Set the page crop box.

	# Select the crop region to be used for drawing.
	draw.SetPageBox(Page::E_crop)
	draw.SetDPI(900)  # Set the output image resolution to 900 DPI.
	draw.Export(page, output_path + "tiger_zoom_900dpi.png", "PNG")
	puts "Example 5: tiger_zoom_900dpi.png"

	# -------------------------------------------------------------------------------
	# Example 6)
	draw.SetImageSize(50, 50)	# Set the thumbnail to be 50x50 pixel image.
	draw.Export(page, output_path + "tiger_zoom_50x50.png", "PNG")
	puts "Example 6: tiger_zoom_50x50.png"

	cmyk_hint = hint_set.CreateDict
	cmyk_hint.PutName("ColorSpace", "CMYK")
	
	#--------------------------------------------------------------------------------
	# Example 6) Convert the first PDF page to CMYK TIFF at 92 DPI.
	# A three step tutorial to convert PDF page to an image
	# A) Open the PDF document
	doc = PDFDoc.new(input_path + "tiger.pdf")
	# Initialize the security handler, in case the PDF is encrypted.
	doc.InitSecurityHandler
	
	# The output resolution is set to 92 DPI.
	draw.SetDPI(92)
	
	# C) Rasterize the first page in the document and save the result as TIFF.
	pg = doc.GetPage(1)
	draw.Export(pg, output_path + "out1.tif", "TIFF", cmyk_hint)
	puts "Example 7: out1.tif"
		
	doc.Close

	# A) Open the PDF document.
	doc = PDFDoc.new(input_path + "tiger.pdf")
	# Initialize the security handler, in case the PDF is encrypted.
	doc.InitSecurityHandler  

	# B) Get the page matrix 
	pg = doc.GetPage(1)
	box = Page::E_crop
	mtx = pg.GetDefaultMatrix(true, box)
	# We want to render a quadrant, so use half of width and height
	pg_w = pg.GetPageWidth(box) / 2
	pg_h = pg.GetPageHeight(box) / 2

	# C) Scale matrix from PDF space to buffer space
	dpi = 96.0
	scale = dpi / 72.0 # PDF space is 72 dpi
	buf_w = ((scale * pg_w).floor).to_i
	buf_h = ((scale * pg_h).floor).to_i
	bytes_per_pixel = 4 # BGRA buffer
	buf_size = buf_w * buf_h * bytes_per_pixel
	mtx.Translate(0, -pg_h) # translate by '-pg_h' since we want south-west quadrant
	mtx = Matrix2D.new(scale, 0, 0, scale, 0, 0).Multiply(mtx)

	# D) Rasterize page into memory buffer, according to our parameters
	rast = PDFRasterizer.new
	buf = rast.Rasterize(pg, buf_w, buf_h, buf_w * bytes_per_pixel, bytes_per_pixel, true, mtx)

	# buf now contains raw BGRA bitmap.
	puts "Example 8: Successfully rasterized into memory buffer."

	#--------------------------------------------------------------------------------
	# Example 9) Export raster content to PNG using different image smoothing settings. 
	text_doc = PDFDoc.new(input_path + "lorem_ipsum.pdf")
	text_doc.InitSecurityHandler

	draw.SetImageSmoothing(false, false)
	filename = "raster_text_no_smoothing.png"
	draw.Export(text_doc.GetPageIterator.Current, output_path + filename)
	puts "Example 9 a): " + filename + ". Done."

	filename = "raster_text_smoothed.png"
	# default quality bilinear resampling
	draw.SetImageSmoothing(true, false)
	draw.Export(text_doc.GetPageIterator.Current, output_path + filename)
	puts "Example 9 b): " + filename + ". Done."

	filename = "raster_text_high_quality.png"
	# high quality area resampling
	draw.SetImageSmoothing(true, true)
	draw.Export(text_doc.GetPageIterator.Current, output_path + filename)
	puts "Example 9 c): " + filename + ". Done."

	#--------------------------------------------------------------------------------
	# Example 10) Export separations directly, without conversion to an output colorspace

	separation_doc = PDFDoc.new(input_path + "op_blend_test.pdf")
	separation_doc.InitSecurityHandler
	separation_hint = hint_set.CreateDict
	separation_hint.PutName("ColorSpace", "Separation")
	draw.SetDPI(96)
	draw.SetImageSmoothing(true, true)
	draw.SetOverprint(PDFRasterizer::E_op_on)

	filename = "merged_separations.png"
	draw.Export(separation_doc.GetPageIterator.Current, output_path + filename, "PNG")
	puts "Example 10 a): " + filename + ". Done."

	filename = "separation"
	draw.Export(separation_doc.GetPageIterator.Current, output_path + filename, "PNG", separation_hint)
	puts "Example 10 b): " + filename + "_[ink].png. Done."

	filename = "separation_NChannel.tif"
	draw.Export(separation_doc.GetPageIterator.Current, output_path + filename, "TIFF", separation_hint)
	puts "Example 10 c): " + filename + ". Done."
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