diff --git a/AGENTS.md b/AGENTS.md
index fb83122..bd107e6 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -51,7 +51,7 @@ Electron + electron-vite + React 终端工具（本地终端 / SSH / SFTP）。
 
 - 终端主题由 xterm 主题派生 UI 配色：`src/renderer/src/theme/chrome.ts` 的 `applyChromeTheme` 写入 `--chrome-bg/-bg-deep/-border/-hover` CSS 变量，antd token 在 `main.tsx` ThemedConfigProvider 派生
 - 标签强调色：`settings.tabAccentColor`（默认 `#3fb950`），经 `--tab-accent` CSS 变量生效
-- 背景图（`settings.terminal.backgroundImage`）：图片层 `.term-bg-image` 在 xterm 画布之下（`terminal.css`），xterm 背景设 `#00000000` 透明。**图片模式下的两条铁律**：① `.terminal-view.has-bg-image .terminal-view-dock` 强制深色底衬 `#0d1117`，不能用 `--chrome-bg`——浅色主题下它是白色，调低透明度会把图洗白而不是压暗；② `minimumContrastRatio` 从 1 提到 4.5（WCAG AA，与 VS Code 终端默认值一致；TerminalView 构造与设置热更两处都要改；注意正确拼写是 `minimumContrastRatio`，`minContrastRatio` 会被静默忽略），xterm 的对比度计算把透明背景当黑色亮度，会把浅色主题的深色前景自动提亮到可读。无图时保持 1 不动主题配色
+- 背景图（`settings.terminal.backgroundImage`）：图片层 `.term-bg-image` 在 xterm 画布之下（`terminal.css`），xterm 背景设 `#00000000` 透明。**图片模式下的三条铁律**：① `.terminal-view.has-bg-image .terminal-view-dock` 强制深色底衬 `#0d1117`，不能用 `--chrome-bg`——浅色主题下它是白色，调低透明度会把图洗白而不是压暗；② `minimumContrastRatio` 从 1 提到 4.5（WCAG AA，与 VS Code 终端默认值一致；TerminalView 构造与设置热更两处都要改；注意正确拼写是 `minimumContrastRatio`，`minContrastRatio` 会被静默忽略），xterm 的对比度计算把透明背景当黑色亮度，会把浅色主题的深色前景自动提亮到可读。无图时保持 1 不动主题配色。③ 压暗层（`settings.terminal.backgroundImageDim`，0–90，**默认 0**）：`.term-bg-dim` 纯黑 scrim 在 DOM 序上位于 `.term-bg-image` 之后、xterm（z-index:1）之下（同在 z-index:0 层，靠 DOM 序压图），与透明度的区别是透明度把图与深色底衬混合、压暗在图之上叠黑（保饱和但整体变暗）；**dim=0 时 TerminalView 不渲染该层，零成本**
 
 ## 终端尺寸同步
 
diff --git a/src/renderer/src/settings/ThemeSettingsTab.tsx b/src/renderer/src/settings/ThemeSettingsTab.tsx
index 92d47d7..ef1eec9 100644
--- a/src/renderer/src/settings/ThemeSettingsTab.tsx
+++ b/src/renderer/src/settings/ThemeSettingsTab.tsx
@@ -32,6 +32,7 @@ export function ThemeSettingsTab({
   const setCustomThemes = useSettingsStore((s) => s.setCustomThemes)
   const activeTheme = useResolvedTheme()
   const [opacityDraft, setOpacityDraft] = useState<number | null>(null)
+  const [dimDraft, setDimDraft] = useState<number | null>(null)
 
   const themeCards = useMemo(
     () => [...BUILTIN_THEMES, ...settings.customThemes],
@@ -90,6 +91,26 @@ export function ThemeSettingsTab({
           />
         </div>
       )}
+      {settings.terminal.backgroundImage !== '' && (
+        <div className="theme-accent-row">
+          <div>
+            <div className="settings-block-label">{t('settings.theme.backgroundImageDim')}</div>
+            <div className="settings-block-hint">{t('settings.theme.backgroundImageDimDesc')}</div>
+          </div>
+          <Slider
+            style={{ width: 200 }}
+            min={0}
+            max={90}
+            step={5}
+            value={dimDraft ?? settings.terminal.backgroundImageDim}
+            onChange={(v) => setDimDraft(v)}
+            onChangeComplete={(v) => {
+              setDimDraft(null)
+              void updateTerminal({ backgroundImageDim: v })
+            }}
+          />
+        </div>
+      )}
       <div className="theme-accent-row">
         <div>
           <div className="settings-block-label">{t('settings.theme.accent')}</div>
diff --git a/src/renderer/src/terminal/TerminalView.tsx b/src/renderer/src/terminal/TerminalView.tsx
index 4e76f35..871f0a3 100644
--- a/src/renderer/src/terminal/TerminalView.tsx
+++ b/src/renderer/src/terminal/TerminalView.tsx
@@ -1400,6 +1400,14 @@ export const TerminalView: ForwardRefExoticComponent<TerminalViewProps & { ref?:
               }}
             />
           )}
+          {settings.terminal.backgroundImage !== '' && settings.terminal.backgroundImageDim > 0 && (
+            <div
+              className="term-bg-dim"
+              style={{
+                opacity: Math.min(90, Math.max(0, settings.terminal.backgroundImageDim)) / 100
+              }}
+            />
+          )}
           {dead && (
             <div className="term-dead-mask">
               <div>{t('terminal.dead.message', { code: exitCode })}</div>
diff --git a/src/renderer/src/terminal/terminal.css b/src/renderer/src/terminal/terminal.css
index adf6676..d8854b6 100644
--- a/src/renderer/src/terminal/terminal.css
+++ b/src/renderer/src/terminal/terminal.css
@@ -380,6 +380,17 @@
   pointer-events: none;
 }
 
+/* Black scrim between the background image and the xterm screen: dims the
+   image without washing it out (unlike opacity, which blends toward the dark
+   dock base), so bright images stay readable at any opacity. */
+.term-bg-dim {
+  position: absolute;
+  inset: 0;
+  z-index: 0;
+  background: #000;
+  pointer-events: none;
+}
+
 .terminal-view-dock > .xterm {
   position: relative;
   z-index: 1;
diff --git a/src/shared/i18n/dicts/en/settings.ts b/src/shared/i18n/dicts/en/settings.ts
index 315ede4..70d9205 100644
--- a/src/shared/i18n/dicts/en/settings.ts
+++ b/src/shared/i18n/dicts/en/settings.ts
@@ -288,6 +288,8 @@ const settings: Record<string, string> = {
   'settings.theme.chooseImage': 'Choose image',
   'settings.theme.clearImage': 'Remove',
   'settings.theme.imageOpacity': 'Image opacity',
+  'settings.theme.backgroundImageDim': 'Background dim',
+  'settings.theme.backgroundImageDimDesc': 'Overlays a black dim layer on top of the image; text is brightened automatically. 30–50% works well for bright images',
   'settings.theme.customBadge': 'Custom',
   'settings.theme.deleteTitle': 'Delete custom theme',
   'settings.theme.create': 'New theme',
diff --git a/src/shared/i18n/dicts/ja/settings.ts b/src/shared/i18n/dicts/ja/settings.ts
index 508e366..2b8cc2e 100644
--- a/src/shared/i18n/dicts/ja/settings.ts
+++ b/src/shared/i18n/dicts/ja/settings.ts
@@ -283,6 +283,8 @@ const settings: Record<string, string> = {
   'settings.theme.chooseImage': '画像を選択',
   'settings.theme.clearImage': '削除',
   'settings.theme.imageOpacity': '画像の不透明度',
+  'settings.theme.backgroundImageDim': '背景の減光',
+  'settings.theme.backgroundImageDimDesc': '画像の上に黒い減光レイヤーを重ね、文字は自動で明るくなります。明るい画像は 30–50% が目安です',
   'settings.theme.customBadge': 'カスタム',
   'settings.theme.deleteTitle': 'カスタムテーマを削除',
   'settings.theme.create': '新しいテーマ',
diff --git a/src/shared/i18n/dicts/zh-CN/settings.ts b/src/shared/i18n/dicts/zh-CN/settings.ts
index d05e644..b18f7a0 100644
--- a/src/shared/i18n/dicts/zh-CN/settings.ts
+++ b/src/shared/i18n/dicts/zh-CN/settings.ts
@@ -272,6 +272,8 @@ const settings: Record<string, string> = {
   'settings.theme.chooseImage': '选择图片',
   'settings.theme.clearImage': '移除图片',
   'settings.theme.imageOpacity': '图片不透明度',
+  'settings.theme.backgroundImageDim': '背景压暗',
+  'settings.theme.backgroundImageDimDesc': '在图片之上叠加黑色压暗层，文字随之自动提亮；亮图建议 30–50%',
   'settings.theme.customBadge': '自定义',
   'settings.theme.deleteTitle': '删除自定义主题',
   'settings.theme.create': '新建主题',
diff --git a/src/shared/i18n/dicts/zh-TW/settings.ts b/src/shared/i18n/dicts/zh-TW/settings.ts
index 760ff15..0eaecbd 100644
--- a/src/shared/i18n/dicts/zh-TW/settings.ts
+++ b/src/shared/i18n/dicts/zh-TW/settings.ts
@@ -272,6 +272,8 @@ const settings: Record<string, string> = {
   'settings.theme.chooseImage': '選擇圖片',
   'settings.theme.clearImage': '移除圖片',
   'settings.theme.imageOpacity': '圖片不透明度',
+  'settings.theme.backgroundImageDim': '背景壓暗',
+  'settings.theme.backgroundImageDimDesc': '在圖片之上疊加黑色壓暗層，文字隨之自動提亮；亮圖建議 30–50%',
   'settings.theme.customBadge': '自訂',
   'settings.theme.deleteTitle': '刪除自訂主題',
   'settings.theme.create': '新增主題',
diff --git a/src/shared/settings.ts b/src/shared/settings.ts
index 6c44172..7c69ae6 100644
--- a/src/shared/settings.ts
+++ b/src/shared/settings.ts
@@ -112,6 +112,8 @@ export interface TerminalSettings {
   backgroundImage: string
   /** background image layer opacity, 10..100 (%) */
   backgroundImageOpacity: number
+  /** black scrim over the background image, under the text, 0..90 (%); 0 = off */
+  backgroundImageDim: number
 }
 
 export type HighlightMode = 'all' | 'basic' | 'off'
@@ -459,7 +461,8 @@ export const DEFAULT_SETTINGS: AppSettings = {
     highlightThemeColors: false,
     highlightPerHost: false,
     backgroundImage: '',
-    backgroundImageOpacity: 30
+    backgroundImageOpacity: 30,
+    backgroundImageDim: 0
   },
   customThemes: [],
   highlightRules: DEFAULT_HIGHLIGHT_RULES,