Created
July 20, 2024 05:33
-
-
Save zazaulola/0409d84ab61c24032937666bbc01eae6 to your computer and use it in GitHub Desktop.
Basic one-thread image hermite resample
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| const s2l = c => (c > 0.04045 ? ((c + 0.055) / 1.055) ** 2.4 : c / 12.92); | |
| const l2s = c => (c > 0.0031308 ? 1.055 * Math.pow(c, 1 / 2.4) - 0.055 : 12.92 * c); | |
| const LINEAR = new Array(256).fill().map((_, i) => s2l(i / 255)); | |
| onmessage = ({ data: { srcData, srcWidth, srcHeight, dstWidth, dstHeight } }) => { | |
| const { ceil, floor, abs, min, hypot } = Math; | |
| const ratioH = srcHeight / dstHeight; | |
| const ratioW = srcWidth / dstWidth; | |
| const halfRatioW = ceil(ratioW / 2); | |
| const halfRatioH = ceil(ratioH / 2); | |
| const dstData = new Uint8ClampedArray(dstWidth * dstHeight * 4); | |
| for (let dstY = 0; dstY < dstHeight; dstY++) { | |
| for (let dstX = 0; dstX < dstWidth; dstX++) { | |
| let dstOfs = (dstX + dstY * dstWidth) * 4; | |
| let weight = 0; | |
| let sAlp = 0; | |
| let sAA = 0; | |
| let [gxRed, gxGrn, gxBlu, gxAlp] = [0, 0, 0, 0]; | |
| const [centerX, centerY] = [(dstX + 0.5) * ratioW, (dstY + 0.5) * ratioH]; | |
| const [begY, endY] = [floor(dstY * ratioH), min(ceil((dstY + 1) * ratioH), srcHeight)]; | |
| const [begX, endX] = [floor(dstX * ratioW), min(ceil((dstX + 1) * ratioW), srcWidth)]; | |
| for (let srcY = begY; srcY < endY; srcY++) { | |
| const dH = abs(centerY - (srcY + 0.5)) / halfRatioH; | |
| for (let srcX = begX; srcX < endX; srcX++) { | |
| const dW = abs(centerX - (srcX + 0.5)) / halfRatioW; | |
| const far = hypot(dH, dW); | |
| if (far >= 1) { | |
| //pixel too far | |
| continue; | |
| } | |
| //hermite filter | |
| weight = 2 * far ** 3 - 3 * far ** 2 + 1; | |
| const srcOfs = 4 * (srcX + srcY * srcWidth); | |
| //alpha | |
| gxAlp += weight * srcData[srcOfs + 3]; | |
| sAA += weight; | |
| if (srcData[srcOfs + 3] < 255) { | |
| // s *= sD[ofs + 3] / 250; | |
| weight *= srcData[srcOfs + 3] / 255; | |
| } | |
| //colors | |
| gxRed += weight * LINEAR[srcData[srcOfs + 0]]; | |
| gxGrn += weight * LINEAR[srcData[srcOfs + 1]]; | |
| gxBlu += weight * LINEAR[srcData[srcOfs + 2]]; | |
| sAlp += weight; | |
| } | |
| } | |
| dstData[dstOfs + 0] = l2s(gxRed / sAlp) * 255; | |
| dstData[dstOfs + 1] = l2s(gxGrn / sAlp) * 255; | |
| dstData[dstOfs + 2] = l2s(gxBlu / sAlp) * 255; | |
| dstData[dstOfs + 3] = l2s(gxAlp / sAA) * 255; | |
| } | |
| } | |
| postMessage(dstData); | |
| }; |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment