recipes: replace placeholder images with OKLAB dominant color backgrounds

Instead of generating/serving 20px placeholder images with blur CSS, extract
a perceptually accurate dominant color (Gaussian-weighted OKLAB average) and
use it as a solid background-color while the full image loads. Removes
placeholder image generation, blur CSS/JS, and placeholder directory references
across upload flows, API routes, service worker, and all card/hero components.
Adds admin bulk tool to backfill colors for existing recipes.
This commit is contained in:
2026-02-17 18:12:36 +01:00
parent d8f8aec282
commit b8469d4ae2
21 changed files with 592 additions and 108 deletions
+101 -23
View File
@@ -3,18 +3,107 @@ import sharp from 'sharp';
import { generateImageHashFromBuffer, getHashedFilename } from '$utils/imageHash';
import { validateImageFile } from '$utils/imageValidation';
// --- sRGB <-> linear RGB <-> OKLAB color conversions ---
function srgbToLinear(c: number): number {
return c <= 0.04045 ? c / 12.92 : Math.pow((c + 0.055) / 1.055, 2.4);
}
function linearToSrgb(c: number): number {
return c <= 0.0031308 ? c * 12.92 : 1.055 * Math.pow(c, 1 / 2.4) - 0.055;
}
function linearRgbToOklab(r: number, g: number, b: number): [number, number, number] {
const l_ = 0.4122214708 * r + 0.5363325363 * g + 0.0514459929 * b;
const m_ = 0.2119034982 * r + 0.6806995451 * g + 0.1073969566 * b;
const s_ = 0.0883024619 * r + 0.2817188376 * g + 0.6299787005 * b;
const l = Math.cbrt(l_);
const m = Math.cbrt(m_);
const s = Math.cbrt(s_);
return [
0.2104542553 * l + 0.7936177850 * m - 0.0040720468 * s,
1.9779984951 * l - 2.4285922050 * m + 0.4505937099 * s,
0.0259040371 * l + 0.7827717662 * m - 0.8086757660 * s,
];
}
function oklabToLinearRgb(L: number, a: number, b: number): [number, number, number] {
const l = L + 0.3963377774 * a + 0.2158037573 * b;
const m = L - 0.1055613458 * a - 0.0638541728 * b;
const s = L - 0.0894841775 * a - 1.2914855480 * b;
const l3 = l * l * l;
const m3 = m * m * m;
const s3 = s * s * s;
return [
+4.0767416621 * l3 - 3.3077115913 * m3 + 0.2309699292 * s3,
-1.2684380046 * l3 + 2.6097574011 * m3 - 0.3413193965 * s3,
-0.0041960863 * l3 - 0.7034186147 * m3 + 1.7076147010 * s3,
];
}
/**
* Process and save recipe image with multiple versions (full, thumb, placeholder)
* Extract the perceptually dominant color from an image buffer.
* Averages pixels in OKLAB space with a 2D Gaussian kernel biased toward the center.
* Returns a hex string like "#a1b2c3".
*/
export async function extractDominantColor(input: Buffer | string): Promise<string> {
const { data, info } = await sharp(input)
.resize(50, 50, { fit: 'cover' })
.removeAlpha()
.raw()
.toBuffer({ resolveWithObject: true });
const { width, height } = info;
const cx = (width - 1) / 2;
const cy = (height - 1) / 2;
const sigmaX = 0.3 * width;
const sigmaY = 0.3 * height;
let wL = 0, wa = 0, wb = 0, wSum = 0;
for (let y = 0; y < height; y++) {
for (let x = 0; x < width; x++) {
const i = (y * width + x) * 3;
// Gaussian weight based on distance from center
const dx = x - cx;
const dy = y - cy;
const w = Math.exp(-0.5 * ((dx * dx) / (sigmaX * sigmaX) + (dy * dy) / (sigmaY * sigmaY)));
// sRGB [0-255] -> linear [0-1] -> OKLAB
const lr = srgbToLinear(data[i] / 255);
const lg = srgbToLinear(data[i + 1] / 255);
const lb = srgbToLinear(data[i + 2] / 255);
const [L, a, b] = linearRgbToOklab(lr, lg, lb);
wL += w * L;
wa += w * a;
wb += w * b;
wSum += w;
}
}
// Average in OKLAB, convert back to sRGB
const [rLin, gLin, bLin] = oklabToLinearRgb(wL / wSum, wa / wSum, wb / wSum);
const r = Math.round(Math.min(1, Math.max(0, linearToSrgb(rLin))) * 255);
const g = Math.round(Math.min(1, Math.max(0, linearToSrgb(gLin))) * 255);
const b = Math.round(Math.min(1, Math.max(0, linearToSrgb(bLin))) * 255);
return '#' + ((1 << 24) | (r << 16) | (g << 8) | b).toString(16).slice(1);
}
/**
* Process and save recipe image with multiple versions (full, thumb)
* and extract dominant color.
* @param file - The image File object
* @param name - The base name for the image (usually recipe short_name)
* @param imageDir - The base directory where images are stored
* @returns Object with hashedFilename and unhashedFilename
* @returns Object with hashedFilename, unhashedFilename, and dominant color
*/
export async function processAndSaveRecipeImage(
file: File,
name: string,
imageDir: string
): Promise<{ filename: string; unhashedFilename: string }> {
): Promise<{ filename: string; unhashedFilename: string; color: string }> {
console.log('[ImageProcessing] Starting image processing for:', {
fileName: file.name,
recipeName: name,
@@ -58,7 +147,7 @@ export async function processAndSaveRecipeImage(
await sharp(fullBuffer).toFile(fullHashedPath);
await sharp(fullBuffer).toFile(fullUnhashedPath);
console.log('[ImageProcessing] Full size images saved');
console.log('[ImageProcessing] Full size images saved');
// Save thumbnail (800px width) - both hashed and unhashed versions
console.log('[ImageProcessing] Generating thumbnail (800px)...');
@@ -75,28 +164,17 @@ export async function processAndSaveRecipeImage(
await sharp(thumbBuffer).toFile(thumbHashedPath);
await sharp(thumbBuffer).toFile(thumbUnhashedPath);
console.log('[ImageProcessing] Thumbnail images saved');
console.log('[ImageProcessing] Thumbnail images saved');
// Save placeholder (20px width) - both hashed and unhashed versions
console.log('[ImageProcessing] Generating placeholder (20px)...');
const placeholderBuffer = await sharp(buffer)
.resize({ width: 20 })
.toFormat('webp')
.webp({ quality: 60 })
.toBuffer();
console.log('[ImageProcessing] Placeholder buffer created, size:', placeholderBuffer.length, 'bytes');
// Extract dominant color
console.log('[ImageProcessing] Extracting dominant color...');
const color = await extractDominantColor(buffer);
console.log('[ImageProcessing] Dominant color:', color);
const placeholderHashedPath = path.join(imageDir, 'rezepte', 'placeholder', hashedFilename);
const placeholderUnhashedPath = path.join(imageDir, 'rezepte', 'placeholder', unhashedFilename);
console.log('[ImageProcessing] Saving placeholder to:', { placeholderHashedPath, placeholderUnhashedPath });
await sharp(placeholderBuffer).toFile(placeholderHashedPath);
await sharp(placeholderBuffer).toFile(placeholderUnhashedPath);
console.log('[ImageProcessing] Placeholder images saved ✓');
console.log('[ImageProcessing] All image versions processed and saved successfully ✓');
console.log('[ImageProcessing] All image versions processed and saved successfully');
return {
filename: hashedFilename,
unhashedFilename: unhashedFilename
unhashedFilename: unhashedFilename,
color
};
}