1. Tool Overview

The "Shadows/Highlights" tool in Photoshop is a core feature specifically designed for digital photo exposure recovery, primarily addressing issues of "underexposure" (loss of shadow details) and "overexposure" (overly bright highlight areas) in photos. It helps users quickly restore image details and enhance the overall texture of photographs.

1.1 Tool Activation and Interface

• Activation path: In Photoshop's top menu bar, click sequentially on "Image" → "Adjustments" → "Shadows/Highlights" to open the basic tool panel.
• Full settings interface: Click on "Show More Options" at the bottom of the panel to expand the complete settings box containing three core modules: "Shadows," "Highlights," and "Adjustments," enabling more precise parameter control.

2. Shadow Adjustment: Fixing Underexposure

Shadow adjustment's core function is to increase the brightness of shadow areas in photos, compensating for underexposed parts (also known as "shadow compensation") to reveal hidden details in dark areas (such as textures in shadows and object contours). This module contains three key parameters: Amount, Tonal Width, and Radius.

2.1 Core Parameter Analysis

• Amount: Controls the magnitude of brightness enhancement in shadow areas.
  • Value range: 0%~100%, where 0% means no shadow compensation effect (original shadow state), and 100% represents maximum brightness enhancement in shadow areas.
  • Practical tip: Start with lower values (e.g., 20%~30%) and adjust gradually to avoid overly bright shadows that lose gradation and appear overexposed.
• Tonal Width: Defines the size of the "shadow area" range, analogous to the "color tolerance" concept in Photoshop's "Magic Wand Tool."
  • Higher values: A wider range of brightness is affected (not just extremely dark areas, but also darker midtones will be adjusted), making shadow brightening more noticeable.
  • Lower values: Only the extremely dark areas in the image are adjusted with minimal impact on midtones, suitable for precise restoration of local shadows.
• Radius: Controls the "area of influence" for shadow adjustment, similar to the difference between "contiguous" and "non-contiguous" selections in the "Magic Wand Tool."
  • Principle: The radius value should match the size of the shadow area to be restored in the image (e.g., for facial shadows, set radius to 20~30 pixels; for large dark scenes, set radius to 40~50 pixels).
  • Practical suggestion: Since it's difficult to accurately judge area sizes visually, drag the slider left and right to observe the shadow transition effects, adjusting until shadow details are clear and transitions are natural (no obvious color blocks).

2.2 Shadow Adjustment Effect Comparison

• Original image: Loss of shadow details, overall dark image.
• 50% Amount: Moderate enhancement of shadow brightness, some details revealed, initial improvement in image gradation.
• 100% Amount: Maximum enhancement of shadow brightness, all details revealed, but be cautious of potential "haze effect" in shadows requiring subsequent color correction optimization.

3. Highlights Adjustment: Fixing Overexposure

Highlights adjustment's core function is to reduce the brightness of highlight areas in photos, suppressing overly bright areas (also known as "highlight suppression") to recover lost details in highlights (such as overexposed skies, facial reflections, and metallic reflections). Its parameter logic is identical to shadow adjustment, also containing three parameters: "Amount," "Tonal Width," and "Radius."

3.1 Core Parameter Analysis (Corresponding to Shadows)

• Amount: Controls the degree of brightness reduction in highlight areas, where 0% means no effect (original highlight state) and 100% represents minimum highlight brightness (which may cause highlight areas to appear too dark).
  • Common scenarios: When fixing overexposed skies, set amount to 40%~60%; when fixing small reflections (such as glasses reflections), set amount to 20%~30%.
• Tonal Width: Defines the range of "highlight areas," where higher values affect a wider range of brightness (including brighter midtones), while lower values adjust only extremely bright highlight areas.
• Radius: Controls the area of influence for highlight adjustment, matching the size of the highlight area to be restored (e.g., for small reflections, set radius to 10~20 pixels; for large sky areas, set radius to 30~50 pixels).

3.2 Highlights Parameter Comparison Demonstration

Since the human eye is more sensitive to highlight changes, observe parameter differences through the following methods (when practicing, disable shadow compensation by setting shadow "Amount" to 0%):

1. Tonal width comparison: At 25% tonal width, only extremely bright areas (such as sun spots) are suppressed; at 75% tonal width, brighter skies and white object edges are also adjusted, significantly expanding the highlight range.
2. Radius comparison: At 0 pixels radius, highlight adjustment has no transition, easily creating harsh color blocks; at 40 pixels radius, highlights transition naturally with normal areas, creating a more harmonious image.

4. Other Settings Options: Optimizing Image Quality

Below the "Shadows" and "Highlights" modules, there are functions such as "Color Correction," "Midtone Contrast," "Black Clip / White Clip," and "Save as Defaults" for further optimizing photo colors and gradation.

4.1 Color Correction

• Purpose: Controls the "color intensity" of shadow or highlight areas, preventing "haze effect" or pale colors in adjusted shadows/highlights.
• Key tip: Color correction only works when shadow compensation (shadow amount > 0%) or highlight suppression (highlight amount > 0%) is active.
  • Example: After shadow compensation, if shadows appear grayish, appropriately increase shadow color correction values to deepen original shadow colors (such as blues and browns in shadows); after highlight suppression, if the sky appears pale, increase highlight color correction to restore the blue tones of the sky.

4.2 Midtone Contrast

• Purpose: Controls the light-dark bias of "midtone areas" in the image, affecting the overall gradation of photos.
  • Value -100: Midtones bias toward shadows, overall darker image, suitable for creating a profound atmosphere (such as night scenes and shadow portraits).
  • Value +100: Midtones bias toward highlights, overall brighter image, suitable for enhancing image clarity (such as fresh portraits and landscapes).
• Practical suggestion: Adjustment amplitude should be controlled within ±30% to avoid excessive adjustments that distort the image.

4.3 Black Clip and White Clip

• Principle: Analogous to the "shadow merging" or "highlight merging" functions in the "Curves Tool," used to enhance the contrast between black and white fields in images.
  • Black Clip: Increasing values makes shadows darker (merging similar shadows), enhancing shadow contrast; excessively high values cause loss of shadow details (recommended ≤20%).
  • White Clip: Increasing values makes highlights brighter (merging similar highlights), enhancing highlight contrast; excessively high values cause loss of highlight details (recommended ≤20%).
• Example effect: When both shadow compensation and highlight suppression are set to 50% with 30 pixels radius, if both Black Clip and White Clip are set to 20%, the black and white contrast of the image will significantly increase, but be aware of potential minor distortions in shadows/highlights.

4.4 Save as Defaults

• Purpose: Saves all current parameters (shadows, highlights, color correction, etc.) as default values, directly applying these parameters when launching the tool subsequently, suitable for batch processing photos with similar exposure issues (such as backlit photos from the same batch).
• Operation: After adjusting parameters, click "Save as Defaults" at the bottom of the panel; to restore default settings, click "Reset Defaults" when launching the tool next time.

5. Practical Steps Summary

1. Open the photo that needs restoration, and in the menu bar click "Image" → "Adjustments" → "Shadows/Highlights."
2. Check "Show More Options" to expand the full settings panel.
3. Adjust shadows separately: Set highlight "Amount" to 0%, then drag shadow "Amount," "Tonal Width," and "Radius" to restore shadow details.
4. Adjust highlights separately: Set shadow "Amount" to 0%, then drag highlight "Amount," "Tonal Width," and "Radius" to fix overexposed areas.
5. Optimize the image: Use "Color Correction" to adjust shadow/highlight colors, use "Midtone Contrast" to optimize gradation, and fine-tune "Black Clip / White Clip" to enhance contrast.
6. Confirm results: Click "OK" to apply adjustments; if unsatisfied, press "Ctrl+Z" to undo and readjust parameters.