[feat] Add ImageStitch node for concatenating images (#8369)

* [feat] Add ImageStitch node for concatenating images with borders

Add ImageStitch node that concatenates images in four directions with optional borders and intelligent size handling. Features include optional second image input, configurable borders with color selection, automatic batch size matching, and dimension alignment via padding or resizing.

Upstreamed from https://github.com/kijai/ComfyUI-KJNodes with enhancements for better error handling and comprehensive test coverage.

* [fix] Fix CI issues with CUDA dependencies and linting

- Mock CUDA-dependent modules in tests to avoid CI failures on CPU-only runners
- Fix ruff linting issues for code style compliance

* [fix] Improve CI compatibility by mocking nodes module import

Prevent CUDA initialization chain by mocking the nodes module at import time,
which is cleaner than deep mocking of CUDA-specific functions.

* [refactor] Clean up ImageStitch tests

- Remove unnecessary sys.path manipulation (pythonpath set in pytest.ini)
- Remove metadata tests that test framework internals rather than functionality
- Rename complex scenario test to be more descriptive of what it tests

* [refactor] Rename 'border' to 'spacing' for semantic accuracy

- Change border_width/border_color to spacing_width/spacing_color in API
- Update all tests to use spacing terminology
- Update comments and variable names throughout
- More accurately describes the gap/separator between images

comfy_extras/nodes_images.py

@@ -14,6 +14,7 @@ import re
 from io import BytesIO
 from inspect import cleandoc
 import torch
+import comfy.utils
 
 from comfy.comfy_types import FileLocator
 
@@ -229,6 +230,186 @@ class SVG:
             all_svgs_list.extend(svg_item.data)
         return SVG(all_svgs_list)
 
+
+class ImageStitch:
+    """Upstreamed from https://github.com/kijai/ComfyUI-KJNodes"""
+
+    @classmethod
+    def INPUT_TYPES(s):
+        return {
+            "required": {
+                "image1": ("IMAGE",),
+                "direction": (["right", "down", "left", "up"], {"default": "right"}),
+                "match_image_size": ("BOOLEAN", {"default": True}),
+                "spacing_width": (
+                    "INT",
+                    {"default": 0, "min": 0, "max": 1024, "step": 2},
+                ),
+                "spacing_color": (
+                    ["white", "black", "red", "green", "blue"],
+                    {"default": "white"},
+                ),
+            },
+            "optional": {
+                "image2": ("IMAGE",),
+            },
+        }
+
+    RETURN_TYPES = ("IMAGE",)
+    FUNCTION = "stitch"
+    CATEGORY = "image/transform"
+    DESCRIPTION = """
+Stitches image2 to image1 in the specified direction.
+If image2 is not provided, returns image1 unchanged.
+Optional spacing can be added between images.
+"""
+
+    def stitch(
+        self,
+        image1,
+        direction,
+        match_image_size,
+        spacing_width,
+        spacing_color,
+        image2=None,
+    ):
+        if image2 is None:
+            return (image1,)
+
+        # Handle batch size differences
+        if image1.shape[0] != image2.shape[0]:
+            max_batch = max(image1.shape[0], image2.shape[0])
+            if image1.shape[0] < max_batch:
+                image1 = torch.cat(
+                    [image1, image1[-1:].repeat(max_batch - image1.shape[0], 1, 1, 1)]
+                )
+            if image2.shape[0] < max_batch:
+                image2 = torch.cat(
+                    [image2, image2[-1:].repeat(max_batch - image2.shape[0], 1, 1, 1)]
+                )
+
+        # Match image sizes if requested
+        if match_image_size:
+            h1, w1 = image1.shape[1:3]
+            h2, w2 = image2.shape[1:3]
+            aspect_ratio = w2 / h2
+
+            if direction in ["left", "right"]:
+                target_h, target_w = h1, int(h1 * aspect_ratio)
+            else:  # up, down
+                target_w, target_h = w1, int(w1 / aspect_ratio)
+
+            image2 = comfy.utils.common_upscale(
+                image2.movedim(-1, 1), target_w, target_h, "lanczos", "disabled"
+            ).movedim(1, -1)
+
+        # When not matching sizes, pad to align non-concat dimensions
+        if not match_image_size:
+            h1, w1 = image1.shape[1:3]
+            h2, w2 = image2.shape[1:3]
+
+            if direction in ["left", "right"]:
+                # For horizontal concat, pad heights to match
+                if h1 != h2:
+                    target_h = max(h1, h2)
+                    if h1 < target_h:
+                        pad_h = target_h - h1
+                        pad_top, pad_bottom = pad_h // 2, pad_h - pad_h // 2
+                        image1 = torch.nn.functional.pad(image1, (0, 0, 0, 0, pad_top, pad_bottom), mode='constant', value=0.0)
+                    if h2 < target_h:
+                        pad_h = target_h - h2
+                        pad_top, pad_bottom = pad_h // 2, pad_h - pad_h // 2
+                        image2 = torch.nn.functional.pad(image2, (0, 0, 0, 0, pad_top, pad_bottom), mode='constant', value=0.0)
+            else:  # up, down
+                # For vertical concat, pad widths to match
+                if w1 != w2:
+                    target_w = max(w1, w2)
+                    if w1 < target_w:
+                        pad_w = target_w - w1
+                        pad_left, pad_right = pad_w // 2, pad_w - pad_w // 2
+                        image1 = torch.nn.functional.pad(image1, (0, 0, pad_left, pad_right), mode='constant', value=0.0)
+                    if w2 < target_w:
+                        pad_w = target_w - w2
+                        pad_left, pad_right = pad_w // 2, pad_w - pad_w // 2
+                        image2 = torch.nn.functional.pad(image2, (0, 0, pad_left, pad_right), mode='constant', value=0.0)
+
+        # Ensure same number of channels
+        if image1.shape[-1] != image2.shape[-1]:
+            max_channels = max(image1.shape[-1], image2.shape[-1])
+            if image1.shape[-1] < max_channels:
+                image1 = torch.cat(
+                    [
+                        image1,
+                        torch.ones(
+                            *image1.shape[:-1],
+                            max_channels - image1.shape[-1],
+                            device=image1.device,
+                        ),
+                    ],
+                    dim=-1,
+                )
+            if image2.shape[-1] < max_channels:
+                image2 = torch.cat(
+                    [
+                        image2,
+                        torch.ones(
+                            *image2.shape[:-1],
+                            max_channels - image2.shape[-1],
+                            device=image2.device,
+                        ),
+                    ],
+                    dim=-1,
+                )
+
+        # Add spacing if specified
+        if spacing_width > 0:
+            spacing_width = spacing_width + (spacing_width % 2)  # Ensure even
+
+            color_map = {
+                "white": 1.0,
+                "black": 0.0,
+                "red": (1.0, 0.0, 0.0),
+                "green": (0.0, 1.0, 0.0),
+                "blue": (0.0, 0.0, 1.0),
+            }
+            color_val = color_map[spacing_color]
+
+            if direction in ["left", "right"]:
+                spacing_shape = (
+                    image1.shape[0],
+                    max(image1.shape[1], image2.shape[1]),
+                    spacing_width,
+                    image1.shape[-1],
+                )
+            else:
+                spacing_shape = (
+                    image1.shape[0],
+                    spacing_width,
+                    max(image1.shape[2], image2.shape[2]),
+                    image1.shape[-1],
+                )
+
+            spacing = torch.full(spacing_shape, 0.0, device=image1.device)
+            if isinstance(color_val, tuple):
+                for i, c in enumerate(color_val):
+                    if i < spacing.shape[-1]:
+                        spacing[..., i] = c
+                if spacing.shape[-1] == 4:  # Add alpha
+                    spacing[..., 3] = 1.0
+            else:
+                spacing[..., : min(3, spacing.shape[-1])] = color_val
+                if spacing.shape[-1] == 4:
+                    spacing[..., 3] = 1.0
+
+        # Concatenate images
+        images = [image2, image1] if direction in ["left", "up"] else [image1, image2]
+        if spacing_width > 0:
+            images.insert(1, spacing)
+
+        concat_dim = 2 if direction in ["left", "right"] else 1
+        return (torch.cat(images, dim=concat_dim),)
+
+
 class SaveSVGNode:
     """
     Save SVG files on disk.
@@ -318,4 +499,5 @@ NODE_CLASS_MAPPINGS = {
     "SaveAnimatedWEBP": SaveAnimatedWEBP,
     "SaveAnimatedPNG": SaveAnimatedPNG,
     "SaveSVGNode": SaveSVGNode,
+    "ImageStitch": ImageStitch,
 }

nodes.py

@@ -2061,6 +2061,7 @@ NODE_DISPLAY_NAME_MAPPINGS = {
     "ImagePadForOutpaint": "Pad Image for Outpainting",
     "ImageBatch": "Batch Images",
     "ImageCrop": "Image Crop",
+    "ImageStitch": "Image Stitch",
     "ImageBlend": "Image Blend",
     "ImageBlur": "Image Blur",
     "ImageQuantize": "Image Quantize",

tests-unit/comfy_extras_test/image_stitch_test.py

@@ -0,0 +1,240 @@
+import torch
+from unittest.mock import patch, MagicMock
+
+# Mock nodes module to prevent CUDA initialization during import
+mock_nodes = MagicMock()
+mock_nodes.MAX_RESOLUTION = 16384
+
+with patch.dict('sys.modules', {'nodes': mock_nodes}):
+    from comfy_extras.nodes_images import ImageStitch
+
+
+class TestImageStitch:
+
+    def create_test_image(self, batch_size=1, height=64, width=64, channels=3):
+        """Helper to create test images with specific dimensions"""
+        return torch.rand(batch_size, height, width, channels)
+
+    def test_no_image2_passthrough(self):
+        """Test that when image2 is None, image1 is returned unchanged"""
+        node = ImageStitch()
+        image1 = self.create_test_image()
+
+        result = node.stitch(image1, "right", True, 0, "white", image2=None)
+
+        assert len(result) == 1
+        assert torch.equal(result[0], image1)
+
+    def test_basic_horizontal_stitch_right(self):
+        """Test basic horizontal stitching to the right"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=32, width=32)
+        image2 = self.create_test_image(height=32, width=24)
+
+        result = node.stitch(image1, "right", False, 0, "white", image2)
+
+        assert result[0].shape == (1, 32, 56, 3)  # 32 + 24 width
+
+    def test_basic_horizontal_stitch_left(self):
+        """Test basic horizontal stitching to the left"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=32, width=32)
+        image2 = self.create_test_image(height=32, width=24)
+
+        result = node.stitch(image1, "left", False, 0, "white", image2)
+
+        assert result[0].shape == (1, 32, 56, 3)  # 24 + 32 width
+
+    def test_basic_vertical_stitch_down(self):
+        """Test basic vertical stitching downward"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=32, width=32)
+        image2 = self.create_test_image(height=24, width=32)
+
+        result = node.stitch(image1, "down", False, 0, "white", image2)
+
+        assert result[0].shape == (1, 56, 32, 3)  # 32 + 24 height
+
+    def test_basic_vertical_stitch_up(self):
+        """Test basic vertical stitching upward"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=32, width=32)
+        image2 = self.create_test_image(height=24, width=32)
+
+        result = node.stitch(image1, "up", False, 0, "white", image2)
+
+        assert result[0].shape == (1, 56, 32, 3)  # 24 + 32 height
+
+    def test_size_matching_horizontal(self):
+        """Test size matching for horizontal concatenation"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=64, width=64)
+        image2 = self.create_test_image(height=32, width=32)  # Different aspect ratio
+
+        result = node.stitch(image1, "right", True, 0, "white", image2)
+
+        # image2 should be resized to match image1's height (64) with preserved aspect ratio
+        expected_width = 64 + 64  # original + resized (32*64/32 = 64)
+        assert result[0].shape == (1, 64, expected_width, 3)
+
+    def test_size_matching_vertical(self):
+        """Test size matching for vertical concatenation"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=64, width=64)
+        image2 = self.create_test_image(height=32, width=32)
+
+        result = node.stitch(image1, "down", True, 0, "white", image2)
+
+        # image2 should be resized to match image1's width (64) with preserved aspect ratio
+        expected_height = 64 + 64  # original + resized (32*64/32 = 64)
+        assert result[0].shape == (1, expected_height, 64, 3)
+
+    def test_padding_for_mismatched_heights_horizontal(self):
+        """Test padding when heights don't match in horizontal concatenation"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=64, width=32)
+        image2 = self.create_test_image(height=48, width=24)  # Shorter height
+
+        result = node.stitch(image1, "right", False, 0, "white", image2)
+
+        # Both images should be padded to height 64
+        assert result[0].shape == (1, 64, 56, 3)  # 32 + 24 width, max(64,48) height
+
+    def test_padding_for_mismatched_widths_vertical(self):
+        """Test padding when widths don't match in vertical concatenation"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=32, width=64)
+        image2 = self.create_test_image(height=24, width=48)  # Narrower width
+
+        result = node.stitch(image1, "down", False, 0, "white", image2)
+
+        # Both images should be padded to width 64
+        assert result[0].shape == (1, 56, 64, 3)  # 32 + 24 height, max(64,48) width
+
+    def test_spacing_horizontal(self):
+        """Test spacing addition in horizontal concatenation"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=32, width=32)
+        image2 = self.create_test_image(height=32, width=24)
+        spacing_width = 16
+
+        result = node.stitch(image1, "right", False, spacing_width, "white", image2)
+
+        # Expected width: 32 + 16 (spacing) + 24 = 72
+        assert result[0].shape == (1, 32, 72, 3)
+
+    def test_spacing_vertical(self):
+        """Test spacing addition in vertical concatenation"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=32, width=32)
+        image2 = self.create_test_image(height=24, width=32)
+        spacing_width = 16
+
+        result = node.stitch(image1, "down", False, spacing_width, "white", image2)
+
+        # Expected height: 32 + 16 (spacing) + 24 = 72
+        assert result[0].shape == (1, 72, 32, 3)
+
+    def test_spacing_color_values(self):
+        """Test that spacing colors are applied correctly"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=32, width=32)
+        image2 = self.create_test_image(height=32, width=32)
+
+        # Test white spacing
+        result_white = node.stitch(image1, "right", False, 16, "white", image2)
+        # Check that spacing region contains white values (close to 1.0)
+        spacing_region = result_white[0][:, :, 32:48, :]  # Middle 16 pixels
+        assert torch.all(spacing_region >= 0.9)  # Should be close to white
+
+        # Test black spacing
+        result_black = node.stitch(image1, "right", False, 16, "black", image2)
+        spacing_region = result_black[0][:, :, 32:48, :]
+        assert torch.all(spacing_region <= 0.1)  # Should be close to black
+
+    def test_odd_spacing_width_made_even(self):
+        """Test that odd spacing widths are made even"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=32, width=32)
+        image2 = self.create_test_image(height=32, width=32)
+
+        # Use odd spacing width
+        result = node.stitch(image1, "right", False, 15, "white", image2)
+
+        # Should be made even (16), so total width = 32 + 16 + 32 = 80
+        assert result[0].shape == (1, 32, 80, 3)
+
+    def test_batch_size_matching(self):
+        """Test that different batch sizes are handled correctly"""
+        node = ImageStitch()
+        image1 = self.create_test_image(batch_size=2, height=32, width=32)
+        image2 = self.create_test_image(batch_size=1, height=32, width=32)
+
+        result = node.stitch(image1, "right", False, 0, "white", image2)
+
+        # Should match larger batch size
+        assert result[0].shape == (2, 32, 64, 3)
+
+    def test_channel_matching_rgb_to_rgba(self):
+        """Test that channel differences are handled (RGB + alpha)"""
+        node = ImageStitch()
+        image1 = self.create_test_image(channels=3)  # RGB
+        image2 = self.create_test_image(channels=4)  # RGBA
+
+        result = node.stitch(image1, "right", False, 0, "white", image2)
+
+        # Should have 4 channels (RGBA)
+        assert result[0].shape[-1] == 4
+
+    def test_channel_matching_rgba_to_rgb(self):
+        """Test that channel differences are handled (RGBA + RGB)"""
+        node = ImageStitch()
+        image1 = self.create_test_image(channels=4)  # RGBA
+        image2 = self.create_test_image(channels=3)  # RGB
+
+        result = node.stitch(image1, "right", False, 0, "white", image2)
+
+        # Should have 4 channels (RGBA)
+        assert result[0].shape[-1] == 4
+
+    def test_all_color_options(self):
+        """Test all available color options"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=32, width=32)
+        image2 = self.create_test_image(height=32, width=32)
+
+        colors = ["white", "black", "red", "green", "blue"]
+
+        for color in colors:
+            result = node.stitch(image1, "right", False, 16, color, image2)
+            assert result[0].shape == (1, 32, 80, 3)  # Basic shape check
+
+    def test_all_directions(self):
+        """Test all direction options"""
+        node = ImageStitch()
+        image1 = self.create_test_image(height=32, width=32)
+        image2 = self.create_test_image(height=32, width=32)
+
+        directions = ["right", "left", "up", "down"]
+
+        for direction in directions:
+            result = node.stitch(image1, direction, False, 0, "white", image2)
+            assert result[0].shape == (1, 32, 64, 3) if direction in ["right", "left"] else (1, 64, 32, 3)
+
+    def test_batch_size_channel_spacing_integration(self):
+        """Test integration of batch matching, channel matching, size matching, and spacings"""
+        node = ImageStitch()
+        image1 = self.create_test_image(batch_size=2, height=64, width=48, channels=3)
+        image2 = self.create_test_image(batch_size=1, height=32, width=32, channels=4)
+
+        result = node.stitch(image1, "right", True, 8, "red", image2)
+
+        # Should handle: batch matching, size matching, channel matching, spacing
+        assert result[0].shape[0] == 2  # Batch size matched
+        assert result[0].shape[-1] == 4  # Channels matched to max
+        assert result[0].shape[1] == 64  # Height from image1 (size matching)
+        # Width should be: 48 + 8 (spacing) + resized_image2_width
+        expected_image2_width = int(64 * (32/32))  # Resized to height 64
+        expected_total_width = 48 + 8 + expected_image2_width
+        assert result[0].shape[2] == expected_total_width
+