feat: 投影法波谷检测+白底硬切断+帧底部对齐+gifmaker透明GIF

- prompt_agent: 精灵表/瓦片集间隙从2-4px放宽到8-16px纯白
- splitsprite removeWhiteBg: dist<threshold/2直接A=0,消除半透明残留
- splitsprite findCuts: 波峰-波谷检测替代死阈值,归并原阈值回退
- splitsprite alignCenter: 全局画布底部对齐替代独立居中,人物不跳帧
- splitsprite MinFillRatio 调至0.14,MinGapWidth调至2
- 新增 pkg/gifmaker: 统一画布+透明索引0+DisposalBackground
- test_prompt_to_gif 改用gifmaker包
This commit is contained in:
2026-05-25 17:57:01 +08:00
parent f3dfcd3b0b
commit 8309d32d4b
5 changed files with 263 additions and 103 deletions
+116 -23
View File
@@ -58,8 +58,9 @@ func DefaultOptions() *Options {
WhiteThreshold: 40,
GapThreshold: 0.03,
MinGapWidth: 2,
MinFillRatio: 0.3,
MinFillRatio: 0.14,
Trim: true,
CenterAlign: true,
}
}
@@ -70,8 +71,9 @@ func DefaultGreenOptions() *Options {
GreenTolerance: 0.2,
GapThreshold: 0.03,
MinGapWidth: 2,
MinFillRatio: 0.3,
MinFillRatio: 0.14,
Trim: true,
CenterAlign: true,
}
}
@@ -133,14 +135,15 @@ func CenterFrames(frames []image.Image) []image.Image {
return alignCenter(frames)
}
// alignCenter finds the content bounding box per frame, computes the max
// dimensions, then pads each frame so content is centered uniformly.
// alignCenter aligns all frames to a uniform canvas with a fixed reference point.
// Uses bottom-center alignment so characters share a common ground plane across frames,
// preventing drift/jitter in animation playback.
func alignCenter(frames []image.Image) []image.Image {
type contentBox struct {
minX, minY, maxX, maxY int
}
boxes := make([]contentBox, len(frames))
maxW, maxH := 0, 0
maxCW, maxCH := 0, 0
for i, f := range frames {
b := f.Bounds()
@@ -172,29 +175,32 @@ func alignCenter(frames []image.Image) []image.Image {
} else {
boxes[i] = contentBox{minX, minY, maxX, maxY}
}
w := boxes[i].maxX - boxes[i].minX + 1
h := boxes[i].maxY - boxes[i].minY + 1
if w > maxW {
maxW = w
cw := boxes[i].maxX - boxes[i].minX + 1
ch := boxes[i].maxY - boxes[i].minY + 1
if cw > maxCW {
maxCW = cw
}
if h > maxH {
maxH = h
if ch > maxCH {
maxCH = ch
}
}
// Pad by 10% to avoid edge cropping
maxW = maxW * 11 / 10
maxH = maxH * 11 / 10
// Uniform canvas with 10% padding
canvasW := maxCW * 11 / 10
canvasH := maxCH * 11 / 10
// Fixed X center reference: anchor all frames to the same horizontal center
fixedCenterX := canvasW / 2
out := make([]image.Image, len(frames))
for i, f := range frames {
cb := boxes[i]
cw := cb.maxX - cb.minX + 1
ch := cb.maxY - cb.minY + 1
ox := (maxW - cw) / 2
oy := (maxH - ch) / 2
// All frames share the same center-X and bottom-Y anchor
ox := fixedCenterX - cw/2 // consistent horizontal center
oy := canvasH - ch // bottom-align: feet planted at same Y
canvas := image.NewRGBA(image.Rect(0, 0, maxW, maxH))
canvas := image.NewRGBA(image.Rect(0, 0, canvasW, canvasH))
draw.Draw(canvas,
image.Rect(ox, oy, ox+cw, oy+ch),
f,
@@ -229,7 +235,7 @@ type tile struct {
x, y, w, h int
}
// removeWhiteBg removes pixels close to pure white (R,G,B all above threshold).
// removeWhiteBg removes pixels close to pure white (R,G,B all within threshold of 255).
func removeWhiteBg(rgba *image.RGBA, threshold uint8) *image.RGBA {
if threshold == 0 {
threshold = 40
@@ -245,11 +251,14 @@ func removeWhiteBg(rgba *image.RGBA, threshold uint8) *image.RGBA {
continue
}
r8, g8, b8 := uint8(r>>8), uint8(g>>8), uint8(bl>>8)
// Pixel is "white" when all channels are near 255
if int(255-r8) < int(threshold) && int(255-g8) < int(threshold) && int(255-b8) < int(threshold) {
// Calculate alpha: closer to white = more transparent
dist := max(int(255-r8), max(int(255-g8), int(255-b8)))
alpha := float64(dist) / float64(threshold)
// Distance from pure white
dist := max(int(255-r8), max(int(255-g8), int(255-b8)))
if dist < int(threshold)/2 {
// Very close to white — fully transparent
dst.SetRGBA(x, y, color.RGBA{R: r8, G: g8, B: b8, A: 0})
} else if dist < int(threshold) {
// Semi-white — fade alpha
alpha := float64(dist-int(threshold)/2) / float64(int(threshold)/2)
dst.SetRGBA(x, y, color.RGBA{R: r8, G: g8, B: b8, A: uint8(alpha * 255)})
}
}
@@ -378,6 +387,90 @@ func tileFillRatio(rgba *image.RGBA, x0, y0, w, h int) float64 {
}
func findCuts(ratios []float64, threshold float64, minGap int) []int {
n := len(ratios)
if n == 0 {
return nil
}
// Smooth the ratio curve with a moving average (kernel size = minGap)
smoothed := make([]float64, n)
kernel := max(minGap, 3)
for i := 0; i < n; i++ {
sum := 0.0
count := 0
for j := max(0, i-kernel/2); j < min(n, i+kernel/2+1); j++ {
sum += ratios[j]
count++
}
if count > 0 {
smoothed[i] = sum / float64(count)
}
}
// Compute mean to use as reference
mean := 0.0
for _, r := range smoothed {
mean += r
}
mean /= float64(n)
// Find peaks: contiguous regions where smoothed ratio > mean*1.2
type segment struct{ start, end int }
var peaks []segment
i := 0
for i < n {
if smoothed[i] > mean*1.2 {
start := i
for i < n && smoothed[i] > mean*0.8 {
i++
}
peaks = append(peaks, segment{start, i})
} else {
i++
}
}
if len(peaks) < 2 {
// Fallback: use threshold-based gap detection
return findCutsByGap(ratios, threshold, minGap)
}
// Find valleys between adjacent peaks (minimum smoothed ratio between them)
cuts := []int{0}
for p := 0; p < len(peaks)-1; p++ {
valleyStart := peaks[p].end
valleyEnd := peaks[p+1].start
if valleyStart >= valleyEnd {
// Peaks adjacent — cut at midpoint
cuts = append(cuts, (peaks[p].end+peaks[p+1].start)/2)
continue
}
// Find minimum in the valley region
minIdx := valleyStart
minVal := smoothed[valleyStart]
for j := valleyStart + 1; j < valleyEnd; j++ {
if smoothed[j] < minVal {
minVal = smoothed[j]
minIdx = j
}
}
cuts = append(cuts, minIdx)
}
cuts = append(cuts, n)
sort.Ints(cuts)
// Deduplicate
dedup := cuts[:1]
for j := 1; j < len(cuts); j++ {
if cuts[j] != dedup[len(dedup)-1] {
dedup = append(dedup, cuts[j])
}
}
return dedup
}
// findCutsByGap is the original threshold-based fallback.
func findCutsByGap(ratios []float64, threshold float64, minGap int) []int {
n := len(ratios)
isGap := make([]bool, n)
for i, r := range ratios {