Image Opacity Tool
Adjust image transparency and export as PNG
Image Opacity Tool — what it does
Set an image's overall transparency and export it as a PNG that carries the alpha channel. Semi-transparent images are how you build watermark layers, faded backgrounds and overlays that let text stay readable over a picture without editing the picture itself.
When this tool helps
- Creating a faded background image so headline text stays readable over it.
- Preparing a semi-transparent logo to overlay on photos or video frames.
- Making a ghosted reference layer for tracing or alignment work.
How to use it
- Choose the image.
- Set the opacity level.
- Check the preview.
- Process and download the PNG.
Accuracy, limits, and good practice
- Export must be PNG — JPEG has no alpha channel and will flatten the transparency against white.
- Around 15 to 30 percent opacity is the usual range for a background image sitting behind body text.
- Transparency depends on what it sits over: check the result on the actual destination background, not against the editor's white page.
- Test the exported PNG on the actual background it will sit on; opacity that looks subtle on white can disappear entirely on a pale page.
Frequently asked questions
Why does my image look solid again?
It was probably saved or converted to JPEG somewhere downstream, which discards alpha and composites onto white.
Can I make only part of the image transparent?
This sets uniform opacity. For a specific colour, the colour replacer or an editor's selection tools are the right approach.
Do all browsers support PNG transparency?
Yes, universally. Transparent PNG is safe everywhere on the modern web.
Can I use a semi-transparent PNG in a PDF?
Yes, the image stamp tool accepts one, and reducing opacity at export gives you finer control than the stamp setting alone.
Related tools on this site
- Local Blur & Mosaic — Blur or pixelate a selected rectangular image area
- Social Media Image Crop — Crop images to popular social media dimensions
- Device Mockup Generator — Place a screenshot inside phone, browser, or laptop frames
Everything above runs inside this page. Image Opacity Tool needs no account, no upload, and no server round trip — close the tab and nothing is left behind.
圖片透明度調整能做什麼
設定圖片的整體透明度，並輸出帶有 alpha 通道的 PNG。半透明圖片正是製作浮水印圖層、淡化背景與覆蓋層的方式，讓文字壓在圖片上仍然清楚，而不必動到圖片本身。
什麼時候用得上
- 製作淡化的背景圖，讓標題文字壓在上面依然好讀。
- 準備半透明商標，疊在照片或影片畫面上。
- 做出淡淡的參考圖層，用於描圖或對位。
使用步驟
- 選擇圖片。
- 設定透明度。
- 檢視預覽。
- 執行處理並下載 PNG。
精確度、限制與實務建議
- 必須輸出 PNG——JPEG 沒有 alpha 通道，會把透明度壓平成白底。
- 襯在內文後方的背景圖，透明度通常落在 15% 至 30% 之間。
- 透明的效果取決於底下是什麼：請在實際的目的背景上檢查，而不是編輯器的白底。
- 請在實際要放的背景上測試匯出的 PNG；在白底上看起來低調的透明度，在淺色頁面上可能整個消失。
常見問題
為什麼圖片又變成不透明了？
多半是在後續流程中被存成或轉成 JPEG，alpha 被捨棄並合成到白底上。
可以只讓部分區域透明嗎？
此工具設定的是整體透明度。針對特定顏色請用顏色替換工具，或用編輯器的選取工具處理。
所有瀏覽器都支援 PNG 透明嗎？
都支援。透明 PNG 在現代網頁上到處都安全可用。
半透明 PNG 可以用在 PDF 裡嗎？
可以，圖片印章工具接受它；匯出時先降透明度，能比單靠印章設定得到更細緻的控制。
本站相關工具
以上步驟全部在這個頁面內完成，圖片透明度調整 不需要註冊、不上傳檔案、也不經過伺服器，關閉分頁後不會留下任何資料。