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/*
* Copyright (C) 2011-2013 Karlsruhe Institute of Technology
*
* This file is part of Ufo.
*
* This library is free software: you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, either
* version 3 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
kernel void
interpolate (global float *a,
global float *b,
global float *output,
float alpha)
{
const int index = get_global_id(1) * get_global_size(0) + get_global_id(0);
output[index] = (1.0f - alpha) * a[index] + alpha * b[index];
}
/*
* Interpolate two arrays along the horizontal direction, *offset* is a linear
* offset to the first and the output arrays. In stitching, *weight* is used to
* match the mean of the second buffer's overlapping region to the first one's.
*/
kernel void
interpolate_horizontally (global float *a,
global float *b,
global float *output,
const int width,
const int left_width,
const int right_width,
const int offset,
const float weight)
{
const int idx = get_global_id(0);
const int idy = get_global_id(1);
const float alpha = ((float) idx) / (get_global_size (0) - 1.0f);
output[idy * width + idx + offset] = (1.0f - alpha) * a[idy * left_width + idx + offset] +
alpha * weight * b[idy * right_width + idx];
}
kernel void
interpolate_mask_horizontally (global float *input,
global float *mask,
global float *output,
const int use_gradient)
{
const int idx = get_global_id (0);
const int idy = get_global_id (1);
const int width = get_global_size (0);
const int offset = idy * width;
int left = idx, right = idx;
float span, diff;
if (mask[offset + idx]) {
while (left > -1 && mask[offset + left] > 0) {
left--;
}
while (right < width && mask[offset + right] > 0) {
right++;
}
if (left < 0) {
/* Mask spans to the left border, use only the right value */
if (right < width - 1) {
if (use_gradient) {
/* There are two valid pixels on the right, use gradient */
diff = input[offset + right] - input[offset + right + 1];
output[offset + idx] = input[offset + right] + diff * (right - idx);
} else {
output[offset + idx] = input[offset + right];
}
} else if (right == width - 1) {
/* There is only one valid pixel on the right, which is the only
* valid pixel in this row, so use it's value everywhere */
output[offset + idx] = input[offset + right];
} else {
/* All pixels in this row are invalid, just copy the input */
output[offset + idx] = input[offset + idx];
}
} else if (right >= width) {
/* Mask spans to the right border, use only the left value */
if (left > 0) {
if (use_gradient) {
/* There are two valid pixels on the left, use gradient */
diff = input[offset + left] - input[offset + left - 1];
output[offset + idx] = input[offset + left] + diff * (idx - left);
} else {
output[offset + idx] = input[offset + left];
}
} else if (left == 0) {
/* There is only one valid pixel on the left, which is the only
* valid pixel in this row, so use it's value everywhere */
output[offset + idx] = input[offset + left];
}
} else {
/* There are valid pixels on both sides, use standard linear
* interpolation */
span = (float) (right - left);
output[offset + idx] = (right - idx) / span * input[offset + left] +
(idx - left) / span * input[offset + right];
}
} else {
output[offset + idx] = input[offset + idx];
}
}
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