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ii-pix
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Combine loops in dither_lookahead and don't bother dithering beyond 

lookahead or edge of screen.
This commit is contained in:
kris 2021-02-05 21:29:09 +00:00
parent 8b48455c8f
commit 722e85f645
1 changed files with 27 additions and 41 deletions
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68
dither.pyx
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@ -79,66 +79,52 @@ def lookahead_options(screen, lookahead, last_pixel_4bit, x):
cdef int dither_lookahead(Dither* dither,
float[:, :, ::1] image_rgb, int x, int y, unsigned char[:, ::1] options_4bit,
float[:, :, ::1] options_rgb, int lookahead, unsigned char[:, ::1] distances, int x_res):
cdef int xl = dither_bounds_xl(dither, x)
cdef int xr = dither_bounds_xr(dither, x_res, x)
# X coord value of larger of dither bounding box or lookahead horizon
cdef int xxr = min(max(x + lookahead, xr), x_res)
cdef int i, j, k, l
cdef int lah_shape0 = 1 << lookahead # 2 ** lookahead
cdef int lah_shape1 = lookahead + xr - xl
# Don't bother dithering past the lookahead horizon or edge of screen.
cdef int xxr = min(x + lookahead, x_res)
cdef int lah_shape1 = xxr - x
cdef int lah_shape2 = 3
cdef float *lah_image_rgb = <float *> malloc(lah_shape0 * lah_shape1 * lah_shape2 * sizeof(float))
# TODO: fold these 3 loops together
for i in range(1 << lookahead):
# Copies of input pixels so we can dither in bulk
for j in range(xxr - x):
for k in range(3):
lah_image_rgb[i * lah_shape1 * lah_shape2 + j * lah_shape2 + k] = image_rgb[y, x+j, k]
# Leave enough space at right of image so we can dither the last of our lookahead pixels.
for j in range(xxr - x, lookahead + xr - xl):
for k in range(3):
lah_image_rgb[i * lah_shape1 * lah_shape2 + j * lah_shape2 + k] = 0
cdef float *lah_image_rgb = <float *> malloc(lah_shape1 * lah_shape2 * sizeof(float))
cdef float[3] quant_error
for i in range(1 << lookahead):
for j in range(xxr - x):
xl = dither_bounds_xl(dither, j)
xr = dither_bounds_xr(dither, x_res - x, j)
# Don't update the input at position x (since we've already chosen
# fixed outputs), but do propagate quantization errors to positions >x
# so we can compensate for how good/bad these choices were
# options_rgb choices are fixed, but we can still distribute
# quantization error from having made these choices, in order to compute
# the total error
for k in range(3):
quant_error[k] = lah_image_rgb[i * lah_shape1 * lah_shape2 + j * lah_shape2 + k] - options_rgb[i, j, k]
apply_one_line(dither, xl, xr, j, &lah_image_rgb[i * lah_shape1 * lah_shape2], lah_shape2, quant_error)
cdef unsigned char bit4
cdef int best
cdef int best_error = 2**31-1
cdef int total_error
cdef long flat, dist
cdef long r, g, b
for i in range(1 << lookahead):
# Working copy of input pixels
for j in range(xxr - x):
for k in range(3):
lah_image_rgb[j * lah_shape2 + k] = image_rgb[y, x+j, k]
total_error = 0
for j in range(lookahead):
r = <long>lah_image_rgb[i * lah_shape1 * lah_shape2 + j * lah_shape2 + 0]
g = <long>lah_image_rgb[i * lah_shape1 * lah_shape2 + j * lah_shape2 + 1]
b = <long>lah_image_rgb[i * lah_shape1 * lah_shape2 + j * lah_shape2 + 2]
for j in range(xxr - x):
xl = dither_bounds_xl(dither, j)
xr = dither_bounds_xr(dither, xxr - x, j)
# We don't update the input at position x (since we've already chosen
# fixed outputs), but we do propagate quantization errors to positions >x
# so we can compensate for how good/bad these choices were. i.e. the
# options_rgb choices are fixed, but we can still distribute quantization error
# from having made these choices, in order to compute the total error.
for k in range(3):
quant_error[k] = lah_image_rgb[j * lah_shape2 + k] - options_rgb[i, j, k]
apply_one_line(dither, xl, xr, j, lah_image_rgb, lah_shape2, quant_error)
r = <long>lah_image_rgb[j * lah_shape2 + 0]
g = <long>lah_image_rgb[j * lah_shape2 + 1]
b = <long>lah_image_rgb[j * lah_shape2 + 2]
flat = (r << 16) + (g << 8) + b
bit4 = options_nbit[i, j]
dist = distances[flat, bit4]
total_error += dist ** 2
total_error += dist * dist
if total_error >= best_error:
break
if total_error < best_error:
best_error = total_error
best = i