2nd/10_Wiki/Dev/Topic_CSS/CSS_Masking_PNG.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
css-masking-with-png	CSS Masking with PNG	Frontend	draft	conceptual		mask-image PNG mask CSS masking mask-repeat mask-position		B	0.87	2026-06-23	2026-06-23			css web frontend w3schools masking mask-image images	https://www.w3schools.com/css/css3_masking.asp

CSS Masking with PNG

🎯 한 줄 통찰 (One-line insight)

CSS masking creates a mask layer placed over an element to partially or fully hide portions of it; a PNG image can serve as that mask layer via the mask-image property. [S1]

🧠 핵심 개념 (Core concepts)

• CSS masking — lets you create a mask layer to place over an element to partially or fully hide portions of the element. [S1]
• mask-image — specifies a mask layer image; it can use a PNG image, an SVG image, a CSS gradient, or an SVG <mask> element. [S1]
• Transparency rule — the mask image needs a transparent or semi-transparent area; black indicates fully transparent. [S1]
• -webkit- prefix — examples pair mask-image with -webkit-mask-image for browser support. [S1]

🧩 추출된 패턴 (Extracted patterns)

• PNG as mask — set both -webkit-mask-image and mask-image to url(...) pointing at a PNG with transparent regions. [S1]
• Control tiling — add mask-repeat: no-repeat; to stop the mask image from tiling across the element. [S1]
• Control placement — add mask-position (e.g. center) to set where the mask image starts. [S1]

📖 세부 내용 (Details)

What CSS masking is — CSS masking allows you to create a mask layer to place over an element to partially or fully hide portions of the element. The mask-image property specifies a mask layer image, which can be a PNG image, an SVG image, a CSS gradient, or an SVG <mask> element. [S1]

Using a PNG image as the mask layer — The mask image needs to have a transparent or semi-transparent area. Black indicates fully transparent. [S1]

.mask1 {
  -webkit-mask-image: url(w3logo.png);
  mask-image: url(w3logo.png);
  mask-repeat: no-repeat;
}

Repeating mask layer images — when mask-repeat is omitted, the mask image will be repeated all over the image. [S1]

.mask1 {
  -webkit-mask-image: url(w3logo.png);
  mask-image: url(w3logo.png);
}

Positioning mask images — the mask-position property sets the starting position of a mask image. [S1]

.mask1 {
  -webkit-mask-image: url(w3logo.png);
  mask-image: url(w3logo.png);
  mask-repeat: no-repeat;
  mask-position: center;
}

CSS masking properties reference [S1]

Property	Description
mask-clip	Specifies which area is affected by a mask image
mask-composite	Specifies a compositing operation used on the current mask layer with the mask layers below it
mask-image	Specifies an image to be used as a mask layer for an element
mask-mode	Specifies whether the mask layer image is treated as a luminance mask or as an alpha mask
mask-origin	Specifies the origin position (the mask position area) of a mask layer image
mask-position	Sets the starting position of a mask layer image (relative to the mask position area)
mask-repeat	Specifies how the mask layer image is repeated
mask-size	Specifies the size of a mask layer image
mask-type	Specifies whether an SVG <mask> element is treated as a luminance mask or as an alpha mask

🛠️ 적용 사례 (Applied in summary)

The page's own examples are the applied cases: applying the w3logo.png PNG as a mask layer over a photograph, with no-repeat, default repeat, and centered positioning. No external project/commit applications found in the source.

💻 코드 패턴 (Code patterns)

Apply a non-repeating PNG mask layer (language: CSS):

.mask1 {
  -webkit-mask-image: url(w3logo.png);
  mask-image: url(w3logo.png);
  mask-repeat: no-repeat;
}

⚖️ 모순 및 업데이트 (Contradictions & updates)

No contradictions found in the source.

✅ 검증 상태 및 신뢰도

• 상태: draft
• 검증 단계: conceptual (실제 적용 사례 발견 시 applied/validated로 승격 가능)
• 출처 신뢰도: B (W3Schools — widely used educational reference, not a primary standards body)
• 신뢰 점수: 0.87
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: CSS Tutorial
• 관련 개념: CSS Masking Gradients, CSS Masking SVG, CSS Image Shapes
• 참조 맥락: Referenced when hiding portions of an element using a PNG-based mask layer.

📚 출처 (Sources)

• [S1] W3Schools — CSS Masking with PNG — https://www.w3schools.com/css/css3_masking.asp

📝 변경 이력 (Change history)

• 2026-06-23: Initial draft synthesized from the W3Schools "CSS Masking with PNG" page (Astra wiki-curation, P-Reinforce v3.1 format).