diff --git a/internal/base/image/scale.go b/internal/base/image/scale.go
index 79d6f73..819a3aa 100644
--- a/internal/base/image/scale.go
+++ b/internal/base/image/scale.go
@@ -56,12 +56,12 @@ func (s rasterImageSource) RGBA64At(x, y int) color.RGBA64 {
 	return color.RGBA64{R: uint16(r), G: uint16(g), B: uint16(b), A: uint16(a)}
 }
 
-// drawRasterAxisImage 按像素中心进行轴向缩小，逐行复用横向采样并保留镜像与小数坐标
+// drawRasterAxisImage 按像素中心进行轴向缩放，逐行复用横向采样并保留镜像与小数坐标
 // 入参: dst 目标图像, src 源图像, m 像素变换, op 合成操作
 // 返回: bool 是否使用轴向采样
 func drawRasterAxisImage(dst draw.Image, src image.Image, m [6]float64, op draw.Op) bool {
 	sx, sy := math.Abs(m[0]), math.Abs(m[3])
-	if m[1] != 0 || m[2] != 0 || sx == 0 || sy == 0 || sx > 1 || sy > 1 || sx == 1 && sy == 1 {
+	if m[1] != 0 || m[2] != 0 || sx == 0 || sy == 0 {
 		return false
 	}
 	for _, v := range m {
@@ -77,6 +77,9 @@ func drawRasterAxisImage(dst draw.Image, src image.Image, m [6]float64, op draw.
 	if r.Empty() {
 		return true
 	}
+	if float64(r.Dx())*math.Min(float64(r.Dy()), math.Ceil(4*math.Max(1, sy))+2) > rasterScaleBufferLimit/32 {
+		return false
+	}
 	xs := rasterImageAxis(r.Min.X, r.Max.X, b.Min.X, b.Max.X, m[0], m[4])
 	ys := rasterImageAxis(r.Min.Y, r.Max.Y, b.Min.Y, b.Max.Y, m[3], m[5])
 	if len(xs) == 0 || len(ys) == 0 {
@@ -142,7 +145,7 @@ func drawRasterAxisImage(dst draw.Image, src image.Image, m [6]float64, op draw.
 // 返回: []rasterAxisSample 轴向采样表
 func rasterImageAxis(first, end, source, limit int, scale, offset float64) []rasterAxisSample {
 	result := make([]rasterAxisSample, 0, end-first)
-	argument := math.Abs(scale)
+	argument := math.Min(1, math.Abs(scale))
 	support := draw.CatmullRom.Support / argument
 	for pixel := first; pixel < end; pixel++ {
 		center := (float64(pixel) + .5 - offset) / scale
@@ -228,7 +231,7 @@ func rasterImageWriteRow(dst draw.Image, output *image.RGBA64, values []rasterIm
 	draw.Draw(dst, image.Rect(x, y, x+len(values), y+1), output, image.Point{}, op)
 }
 
-// DrawPixels 对轴向缩小使用可分离采样，其余变换保留通用路径
+// DrawPixels 对轴向缩放使用可分离采样，其余变换保留通用路径
 // 入参: dst 目标图像, src 源图像, m 按a、b、c、d、e、f排列的像素变换, op 合成操作
 func DrawPixels(dst draw.Image, src image.Image, m [6]float64, op draw.Op) {
 	b := src.Bounds()
diff --git a/ofdgo_pdf_composite_draw.go b/ofdgo_pdf_composite_draw.go
index 611e59f..85a9739 100644
--- a/ofdgo_pdf_composite_draw.go
+++ b/ofdgo_pdf_composite_draw.go
@@ -658,12 +658,27 @@ func (c *pdfCompositor) mask(mask *pdfgo.SoftMask, inherited *pdfgo.ColorSpace)
 			c.scratch.masks.release(result)
 		}
 	}()
+	values := make(map[[4]float64]float64)
+	var previous [4]float64
+	var opacity float64
 	for i, pixel := range pixels {
 		if i%pdfCompositeTileSize == 0 {
 			if err := c.importer.ctx.Err(); err != nil {
 				return nil, err
 			}
 		}
+		key := [4]float64{pixel.Alpha}
+		if mask.Subtype == "Luminosity" {
+			key = pixel.Values
+		}
+		if i != 0 && key == previous {
+			result[i] = opacity
+			continue
+		}
+		if cached, ok := values[key]; ok {
+			previous, opacity, result[i] = key, cached, cached
+			continue
+		}
 		v := pixel.Alpha
 		if mask.Subtype == "Luminosity" {
 			v, err = space.Luminosity(pixel.Values[:space.Components()], "RelativeColorimetric")
@@ -675,6 +690,10 @@ func (c *pdfCompositor) mask(mask *pdfgo.SoftMask, inherited *pdfgo.ColorSpace)
 		if err != nil {
 			return nil, err
 		}
+		previous, opacity = key, result[i]
+		if len(values) < 2*pdfCompositeTileSize {
+			values[key] = opacity
+		}
 	}
 	complete = true
 	c.masks[mask] = result