Using python to write a new layer to a psd file

image_to_psd_layer.py

"""
  Exmample of how to read a PSD in python, add a layer and write image data to it. 
  With this you can automate a bunch of PSD functionality
  
"""

import pytoshop
from pytoshop import layers
from pytoshop.enums import BlendMode
import numpy as np
import cv2

# This is creative commons. Use it and be cool to one another.
# psd-tools needs this functionality and if you have time I'm sure a PR would be highly appreciated

# urls for images
my_image_url = "art/my_cool_image.png"


def create_rgba_data_for_image(image_url: str) -> np.ndarray:
    """
    Reads in image and converts it to RGBA

    :param image_url: The url of the image to be converted eg. art/my_image.png
    :return: The image as a numpy array
    """

    # do initial read
    image = cv2.imread(image_url, 1)  # reads using opencv and as rgb format
    # Convert the image to RGBA
    rgba_image = cv2.cvtColor(image, cv2.COLOR_BGR2RGBA)  # todo: see if we can do this in one step
    return rgba_image  # Return the numpy array directly


def insert_psd_layer(psd, image_data, layer_name="a new photoshop layer appears!", blending_mode=BlendMode.normal):
    """
    Inserts a layer into a PSD
    Expects a PSD to exist, but there are other methods which will create a PSD from scratch

    :param psd: The PSD to insert the layer into. This is done using `psd = pytoshop.read(fd)` after you open the image as a read binary
    :param image_data: The image data as a numpy array. Use the function `create_rgba_data_for_image` to convert an image to RGBA
    :param layer_name: The name of the layer to be inserted
    :param blending_mode: The blending mode of the layer to be inserted. Use `BlendMode.normal` for normal blending
    """
    num_channels = image_data.shape[2]
    channel_data = [layers.ChannelImageData(image=image_data[:, :, i], compression=1) for i in range(num_channels)]

    layer_channels = {
        -1: channel_data[3] if num_channels > 3 else None,  # if no alpha channel, set to none
        0: channel_data[0],
        1: channel_data[1],
        2: channel_data[2],
    }
    layer_channels = {k: v for k, v in layer_channels.items() if v is not None}

    layer_record = layers.LayerRecord(
        channels=layer_channels,
        top=0,
        bottom=image_data.shape[0],
        left=0,
        right=image_data.shape[1],
        blend_mode=blending_mode,
        name=layer_name,
        opacity=255,
    )
    psd.layer_and_mask_info.layer_info.layer_records.append(layer_record)
    return psd


##########################################################
# EXAMPLE TO READ AND WRITE A PSD WITH A FANCY NEW LAYER #
##########################################################

with open("example2.psd", "rb") as fd:
    psd = pytoshop.read(fd)

    # Get the RGBA image data
    rgba_image_data = create_rgba_data_for_image(my_image_url)

    # Insert the layer
    insert_psd_layer(psd, rgba_image_data, "test layer name", BlendMode.normal)  # Use string 'norm' for blending_mode

    # Write the modified PSD to a new file
    # Writing to the same open file is weird and can probably be done, but I can't be bothered dealing with it atm
    with open("example1.psd", "wb") as fd2:
        psd.write(fd2)

<3 to AuthorSultra for the example in his repo
https://github.com/AuthorSultra/Layer-PSD/blob/main/scripts/layer_divider_modules/mask_utils.py#L5
And of course to psd-tools and pytoshop for building packages