resize.py

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#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; either version 2
#  of the License, or (at your option) any later version.
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# Args:
# img input path
# size X
# img output path

# example usage:
# blender --background --factory-startup --python resize.py -- "C:\big image.hdr" 200 "C:\small image.jpg"

import bpy
import sys
from math import floor

argv = sys.argv
argv = argv[argv.index("--") + 1 :]  # Get all args after  '--'
FILEPATH, SIZE_X, OUTPATH = argv
SIZE_X = int(SIZE_X)

context = bpy.context
scene = context.scene

scene.use_nodes = True
node_tree = scene.node_tree

# Remove default nodes, except composite
n_comp = None
for n in node_tree.nodes:
    if not n.type == "COMPOSITE":
        node_tree.nodes.remove(n)
    else:
        n_comp = n

img = bpy.data.images.load(FILEPATH)
n_img = node_tree.nodes.new("CompositorNodeImage")
n_img.image = img

n_blur = node_tree.nodes.new("CompositorNodeBlur")
n_blur.filter_type = "FLAT"
n_blur.size_x = floor(img.size[0] / SIZE_X / 2)
n_blur.size_y = n_blur.size_x

n_scale = node_tree.nodes.new("CompositorNodeScale")
n_scale.space = "RENDER_SIZE"
n_scale.frame_method = "CROP"

# Links
links = node_tree.links
links.new(n_img.outputs[0], n_blur.inputs[0])
links.new(n_blur.outputs[0], n_scale.inputs[0])
links.new(n_scale.outputs[0], n_comp.inputs[0])

# Render
r = scene.render
r.image_settings.file_format = "JPEG"
r.image_settings.quality = 95
r.resolution_x = SIZE_X
SIZE_Y = floor(SIZE_X / (img.size[0] / img.size[1]))
r.resolution_y = SIZE_Y
r.resolution_percentage = 100
r.filepath = OUTPATH

bpy.ops.render.render(write_still=True)