I. Foundational Adjustments:
1. Open Your Image in Photoshop: Start with a well-exposed, high-resolution image. The better the source, the better the final result.
2. Duplicate the Background Layer (Ctrl/Cmd + J): This protects your original and allows you to work non-destructively.
3. Lower Overall Exposure: This is the most crucial step. There are several ways to do this:
* Curves Adjustment Layer: This is the preferred method for fine-grained control. Add a Curves adjustment layer (Layer > New Adjustment Layer > Curves). Click near the middle of the curve and drag it downwards to darken the entire image. How much you lower it depends on the original exposure, but aim for a substantial reduction. A slightly S-shaped curve can add contrast.
* Levels Adjustment Layer: (Layer > New Adjustment Layer > Levels). Similar to Curves, but uses sliders. Move the midtone (gray) slider towards the right to darken the image. Adjust the black and white sliders as needed for contrast.
* Camera Raw Filter (Filter > Camera Raw Filter): Allows you to adjust several settings, including Exposure, Contrast, Highlights, Shadows, Whites, and Blacks. This gives you a more comprehensive range of adjustments in one panel.
Important: Don't go too dark right away. You'll be brightening certain areas later. Aim for a believable twilight level.
II. Introduce Nighttime Color Tones:
1. Color Balance Adjustment Layer (Layer > New Adjustment Layer > Color Balance): This is where you shift the colors towards a nighttime palette.
* In the Midtones, shift the sliders towards:
* Blues and Cyans (to cool down the image)
* A touch of Magenta (to add a slightly purplish hue)
* In the Shadows, push towards:
* Blues and Cyans (more heavily than in the midtones)
* In the Highlights, you might keep them relatively neutral or even lean towards a slight yellow/orange to mimic street lights reflecting on buildings.
2. Photo Filter Adjustment Layer (Layer > New Adjustment Layer > Photo Filter): Another way to add a color cast. Choose a cool filter like "Cooling Filter (80)" or "Cooling Filter (82)" and adjust the density. Less is often more.
3. Selective Color Adjustment Layer (Layer > New Adjustment Layer > Selective Color): This allows you to adjust specific color ranges. For example, you can reduce yellow in the yellows to minimize unwanted yellow casts from streetlights.
III. Adding Light Sources and Glows:
1. Identify Potential Light Sources: Look for windows, streetlights, car headlights, neon signs, etc.
2. Create Light Sources (the core of the technique): The method depends on the situation. Here are a few common techniques:
* Streetlights/Glows:
* New Empty Layer: Create a new layer (Ctrl/Cmd + Shift + N) and set its blend mode to "Screen" or "Linear Dodge (Add)."
* Brush Tool (B): Choose a soft, round brush with low opacity (5-20%).
* Color: Select a warm yellow or orange color.
* Paint: Gently paint around the streetlights to create a glow. Build up the color in the center. Use larger brush sizes for more diffused glows, and smaller sizes for brighter, focused light.
* Glow Around Objects: Create a new layer and repeat the above for objects near the source that would receive light.
* Windows:
* New Empty Layer: Create a new layer. Set its blend mode to "Screen" or "Linear Dodge (Add)."
* Rectangular Marquee Tool (M): Select the window areas.
* Fill (Alt/Option + Delete): Fill the selection with a light yellow, orange, or warm white color.
* Gaussian Blur (Filter > Blur > Gaussian Blur): Apply a slight blur to soften the edges of the light. Adjust the blur radius for the desired effect.
* Variation: For visible interiors. Start with a dark color and slowly paint over the windows with lighter colors with brush, like someone turning on a lamp.
* Car Headlights:
* New Empty Layer: Create a new layer. Set its blend mode to "Screen" or "Linear Dodge (Add)."
* Brush Tool (B): Use a bright white or slightly blue-tinted white brush.
* Paint: Paint the headlights. You can also create light trails using a motion blur filter.
* Motion Blur (Filter > Blur > Motion Blur): Apply a Motion Blur along the direction of travel to simulate the light trail.
* Lens Flare (Filter > Render > Lens Flare): *Use sparingly!* A very subtle lens flare can add realism, but overdoing it looks artificial. Experiment with different lens flare types.
3. Layer Masks: Use layer masks to refine the light sources and prevent them from spilling onto areas where they shouldn't be. For example, use a mask to confine a streetlight glow to just the area around the light.
IV. Details and Finishing Touches:
1. Sky Replacement (If Needed): The daytime sky often needs to be replaced with a night sky.
* Download/Find a Night Sky Image: Get a high-quality night sky image (search for "starry sky" or "night sky" on sites like Unsplash or Pexels).
* Place the Sky Image: Place the night sky image into your document (File > Place Embedded or File > Place Linked). Position it behind your main image layer.
* Masking: Create a mask on your main image layer to reveal the night sky. Use the Brush Tool (B) with a soft brush and black as your foreground color to paint out the daytime sky. Feather the edges of the mask for a smooth transition.
* Blending: Adjust the blending mode of the sky layer or the main image layer to achieve a seamless integration (e.g., "Multiply," "Darken," or "Color Burn"). Experiment to see what looks best.
* Matching Colors: Use adjustment layers (Color Balance, Curves) on the sky layer to match its color and brightness to the rest of the scene.
2. Stars (Optional): You can add stars using a custom brush or by creating them manually.
* Brush Method: Search online for star brushes. Use a small, white brush with varying sizes and opacity to paint stars in the sky.
* Manual Method: Create a new layer. Fill it with black. Add Noise (Filter > Noise > Add Noise) with a high amount. Use Levels to reduce the black and leave small white dots. Apply a Gaussian Blur to soften the stars.
3. Increased Contrast: A subtle increase in contrast can make the night scene more dynamic. Use a Curves or Levels adjustment layer.
4. Noise: A very slight amount of noise (Filter > Noise > Add Noise) can add a touch of realism, especially if the original image is very clean. Use a small amount (1-2%) and make sure it's uniform (Monochromatic checkbox).
5. Sharpening: Apply a final sharpening (Filter > Sharpen > Unsharp Mask) to bring out details. Use it sparingly to avoid artifacts.
V. Tips for Realism:
* Reference Photos: Look at real night photos of urban landscapes for inspiration. Pay attention to the color of the light, the amount of ambient light, and the way light interacts with different surfaces.
* Subtlety: Avoid overdoing any single effect. Night scenes often have a soft, subtle quality.
* Shadows: Pay attention to the shadows. At night, shadows are typically darker and have a different color cast than daytime shadows. You can deepen shadows using Curves or Levels.
* Atmospheric Perspective: In the distance, lights and colors will appear more muted and blueish due to atmospheric haze. You can simulate this with a gradient overlay.
* Light Pollution: Urban areas typically have significant light pollution. The sky might not be completely black, but rather a dark blue or gray.
* Experiment: There's no single "correct" way to do this. Experiment with different techniques and settings until you achieve the desired look.
* Non-Destructive Editing: Use adjustment layers and layer masks so you can always go back and make changes.
Example Workflow:
1. Open image, Duplicate background layer.
2. Curves: Reduce exposure.
3. Color Balance: Add blues/cyans to midtones and shadows.
4. New Layer (Screen): Paint glows around streetlights (yellow/orange).
5. New Layer (Screen): Paint lights in windows (warm white/yellow).
6. Sky Replacement (if needed).
7. Contrast adjustment (Curves/Levels).
8. Noise (subtle).
9. Sharpening.
By following these steps and experimenting, you can transform your daytime urban landscapes into stunning and believable nighttime scenes in Photoshop. Good luck!