"""
Utility functions for manipulating image files such as .png and .pdfs.
Makes use use of the Python Pillow package if working with .png files, and
the PyPDF2 package if manipulating pdf files. Internal imports for all functions
to remove Pyatoa-wide dependencies on these packages for short functions.
"""
import numpy as np
from PIL import Image
from pypdf import PdfMerger
[docs]
def merge_pdfs(fids, fid_out):
"""
Merge a list of pdfs into a single output pdf using the PyPDF2 package.
Any desired order to the pdfs should be set in the list of input fids.
:type fids: list
:param fids: list of paths to .pdf files
:type fid_out: str
:param fid_out: path and name of the resulting output .pdf file
"""
if not fids:
return
merger = PdfMerger()
for fid in fids:
merger.append(fid)
merger.write(fid_out)
merger.close()
[docs]
def imgs_to_pdf(fids, fid_out):
"""
Combine a list of .png files into a single PDF document
:type fids: list
:param fids: list of file ids with full pathnames to be combined
:type fid_out: str
:param fid_out: the name of the file to be saved with full pathname
"""
images = []
for fid in fids:
# PNGs need to be converted to RGB to get alpha to play nice
images.append(Image.open(fid).convert("RGB"))
image_main = images[0]
images = images[1:]
image_main.save(fp=fid_out, format="PDF", resolution=100., save_all=True,
append_images=images)
[docs]
def tile_imgs(fids, fid_out):
"""
Combine a list of images into a single, horizontally tiled image.
:type fids: list
:param fids: list of file ids with full pathnames to be tiled
:type fid_out: str
:param fid_out: the name of the file to be saved with full pathname
"""
# .png files require conversion to properly get the alpha layer
images = []
for fid in fids:
images.append(Image.open(fid).convert("RGBA"))
widths, heights = zip(*(i.size for i in images))
total_width = sum(widths)
max_height = max(heights)
# Create the new image that will be returned
im_out = Image.new(mode="RGBA", size=(total_width, max_height))
x_offset = 0
for im in images:
im_out.paste(im=im, box=(x_offset, 0))
x_offset += im.size[0]
im_out.save(fid_out)
[docs]
def tif_to_array(fid):
"""
Convert GeoTiff images (e.g., ETOPO1 topography) to a numpy array for
conversion and processing
:type fid: str
:param fid: .tif(f) file
:rtype: np.array
:return: array of data contained within the tiff file
"""
try:
im = Image.open(fid)
except Image.DecompressionBombError as e:
# If the image is too large, it will throw an error, we'll just need
# to adjust the acceptable size of the image. This may be bad if you
# don't trust the image! But let's be reckless...
error_str = str(e)
# Assuming the error message looks like:
# 'Image size (N pixels) exceeds...' Trying to get value N
pixels = int(error_str.split()[2][1:])
print(f"setting Image max pixel count to {pixels}")
Image.MAX_IMAGE_PIXELS = pixels
im = Image.open(fid)
imarray = np.array(im)
return imarray