How to grayscale an image

How to grayscale an image

         You can convert color images to their grayscale versions by using `Grayscale` method of the RasterImage class. Also, you can convert vector images for grayscale by rasterizing them using `png` format:

from aspose.imaging import RasterImage, Image, IMultipageImage
from aspose.imaging.imageoptions import PngOptions
from aspose.pycore import as_of, is_assignable
import os

if 'TEMPLATE_DIR' in os.environ:
	templates_folder = os.environ['TEMPLATE_DIR']
else:
	templates_folder = r"C:\Users\USER\Downloads\templates"

delete_output = 'SAVE_OUTPUT' not in os.environ


def delete_file(file):
	if delete_output:
		os.remove(file)
		
		
def grayscale_images():
	obj_init = []
	obj_init.append("jpg")
	obj_init.append("png")
	obj_init.append("bmp")
	obj_init.append("apng")
	obj_init.append("dicom")
	obj_init.append("jp2")
	obj_init.append("j2k")
	obj_init.append("tga")
	obj_init.append("webp")
	obj_init.append("tiff")
	obj_init.append("gif")
	obj_init.append("ico")
	raster_formats = obj_init
	obj_init2 = []
	obj_init2.append("svg")
	obj_init2.append("otg")
	obj_init2.append("odg")
	obj_init2.append("eps")
	obj_init2.append("wmf")
	obj_init2.append("emf")
	obj_init2.append("wmz")
	obj_init2.append("emz")
	obj_init2.append("cmx")
	obj_init2.append("cdr")
	vector_formats = obj_init2
	all_formats = raster_formats
	all_formats.extend(vector_formats)
	for format_ext in all_formats:
		input_file = os.path.join(templates_folder, f"template.{format_ext}")
		
		if not os.path.exists(input_file):
			continue
		
		is_vector_format = format_ext in vector_formats
		if is_vector_format:
			input_file = rasterize_vector_image(format_ext, input_file)

		output_file = os.path.join(templates_folder, f"grayscale_{format_ext}.png")
		print(f"Processing {format_ext}")
		# explicit type casting from Image to RasterImage
		with as_of(Image.load(input_file), RasterImage) as image:
			# Additional code examples can be found at
            # https://apireference.aspose.com/imaging/python-net/aspose.imaging/rasterimage/methods/grayscale
			image.grayscale()
			multi_page = None
			# if image implements an IMultipageImage interface
			if is_assignable(image, IMultipageImage):
				multi_page = as_of(image, IMultipageImage)
			
			if multi_page is not None and multi_page.page_count > 1:
				page_index = 0
				for page in multi_page.pages:
					file_name = f"grayscale_page{page_index}_{format_ext}.png"
					page.save(templates_folder + file_name, PngOptions())
					delete_file(templates_folder + file_name)
					page_index += 1
			else:
				image.save(output_file, PngOptions())
				delete_file(output_file)

		if is_vector_format:
			delete_file(input_file)


def rasterize_vector_image(format_ext, input_file):
	output_file = os.path.join(templates_folder, f"rasterized.{format_ext}.png")
	with Image.load(input_file) as image:
		image.save(output_file, PngOptions())

	return output_file


grayscale_images()