CrossFadeImages

Documentation

• Class name: CrossFadeImages
• Category: KJNodes/image
• Output node: False

The CrossFadeImages node is designed to blend two sequences of images together over a specified number of frames, using a variety of easing functions to control the transition dynamics. This node allows for the creation of smooth transitions between images, enhancing visual storytelling or creating dynamic visual effects.

Input types

Required

• images_i
  • unknown
  • Comfy dtype: IMAGE
  • Python dtype: unknown
• interpolation
  • Specifies the easing function to be used for the transition, affecting how the crossfade between images progresses over time.
  • Comfy dtype: COMBO[STRING]
  • Python dtype: str
• transition_start_index
  • The index in the image sequences where the transition begins, allowing for precise control over the timing of the crossfade.
  • Comfy dtype: INT
  • Python dtype: int
• transitioning_frames
  • The number of frames over which the transition occurs, defining the length of the crossfade effect.
  • Comfy dtype: INT
  • Python dtype: int
• start_level
  • The initial alpha value for the crossfade, determining the starting blend ratio between the two image sequences.
  • Comfy dtype: FLOAT
  • Python dtype: float
• end_level
  • The final alpha value for the crossfade, determining the ending blend ratio between the two image sequences.
  • Comfy dtype: FLOAT
  • Python dtype: float

Output types

• image
  • Comfy dtype: IMAGE
  • The resulting sequence of images after applying the crossfade transition between the two input sequences.
  • Python dtype: torch.Tensor

Usage tips

• Infra type: GPU
• Common nodes: unknown

Source code

class CrossFadeImages:

    RETURN_TYPES = ("IMAGE",)
    FUNCTION = "crossfadeimages"
    CATEGORY = "KJNodes/image"

    @classmethod
    def INPUT_TYPES(s):
        return {
            "required": {
                 "images_1": ("IMAGE",),
                 "images_2": ("IMAGE",),
                 "interpolation": (["linear", "ease_in", "ease_out", "ease_in_out", "bounce", "elastic", "glitchy", "exponential_ease_out"],),
                 "transition_start_index": ("INT", {"default": 1,"min": 0, "max": 4096, "step": 1}),
                 "transitioning_frames": ("INT", {"default": 1,"min": 0, "max": 4096, "step": 1}),
                 "start_level": ("FLOAT", {"default": 0.0,"min": 0.0, "max": 1.0, "step": 0.01}),
                 "end_level": ("FLOAT", {"default": 1.0,"min": 0.0, "max": 1.0, "step": 0.01}),
        },
    } 

    def crossfadeimages(self, images_1, images_2, transition_start_index, transitioning_frames, interpolation, start_level, end_level):

        def crossfade(images_1, images_2, alpha):
            crossfade = (1 - alpha) * images_1 + alpha * images_2
            return crossfade
        def ease_in(t):
            return t * t
        def ease_out(t):
            return 1 - (1 - t) * (1 - t)
        def ease_in_out(t):
            return 3 * t * t - 2 * t * t * t
        def bounce(t):
            if t < 0.5:
                return self.ease_out(t * 2) * 0.5
            else:
                return self.ease_in((t - 0.5) * 2) * 0.5 + 0.5
        def elastic(t):
            return math.sin(13 * math.pi / 2 * t) * math.pow(2, 10 * (t - 1))
        def glitchy(t):
            return t + 0.1 * math.sin(40 * t)
        def exponential_ease_out(t):
            return 1 - (1 - t) ** 4

        easing_functions = {
            "linear": lambda t: t,
            "ease_in": ease_in,
            "ease_out": ease_out,
            "ease_in_out": ease_in_out,
            "bounce": bounce,
            "elastic": elastic,
            "glitchy": glitchy,
            "exponential_ease_out": exponential_ease_out,
        }

        crossfade_images = []

        alphas = torch.linspace(start_level, end_level, transitioning_frames)
        for i in range(transitioning_frames):
            alpha = alphas[i]
            image1 = images_1[i + transition_start_index]
            image2 = images_2[i + transition_start_index]
            easing_function = easing_functions.get(interpolation)
            alpha = easing_function(alpha)  # Apply the easing function to the alpha value

            crossfade_image = crossfade(image1, image2, alpha)
            crossfade_images.append(crossfade_image)

        # Convert crossfade_images to tensor
        crossfade_images = torch.stack(crossfade_images, dim=0)
        # Get the last frame result of the interpolation
        last_frame = crossfade_images[-1]
        # Calculate the number of remaining frames from images_2
        remaining_frames = len(images_2) - (transition_start_index + transitioning_frames)
        # Crossfade the remaining frames with the last used alpha value
        for i in range(remaining_frames):
            alpha = alphas[-1]
            image1 = images_1[i + transition_start_index + transitioning_frames]
            image2 = images_2[i + transition_start_index + transitioning_frames]
            easing_function = easing_functions.get(interpolation)
            alpha = easing_function(alpha)  # Apply the easing function to the alpha value

            crossfade_image = crossfade(image1, image2, alpha)
            crossfade_images = torch.cat([crossfade_images, crossfade_image.unsqueeze(0)], dim=0)
        # Append the beginning of images_1
        beginning_images_1 = images_1[:transition_start_index]
        crossfade_images = torch.cat([beginning_images_1, crossfade_images], dim=0)
        return (crossfade_images, )