[FFmpeg-devel] Add alternative delogo algorithm for my donation

[uwe.freese at gmx.de]

Hello Kyle,
> You should also try vf_removelogo. It is supposedly better than the
> more simple vf_delogo.

I tried (with a box in a PNG mask as logo cover).

That is no alternative both quality wise and from usability point of view:

1. It gave me blurry borders with several pixels widths from outside to 
the inner. They were very symmetrical and showed a 45 degree "lines" 
from the edges to the middle. Hardly the nice blurred box I wanted.

2. If you want to cover the logo by simple coordinates (a box), it's 
unnecessary effort to create a PNG mask with that box in it instead of 
giving the coordinates as parameter.


Because removelogo can handle arbitrary masks and the calculation I 
posted is using a simple rectangular box (and this is my typical use 
case), I suggested to add it to the "delogo" filter.

So my offer stands, would be nice if someone can add this additional mode.

>> Here's the relevant code to add (+ some config variable to set the mode
>> I guess):
>>
>> // Precalculate weights once.
>> void TimgFilterLogoaway::Tplane::calcUweWeightTable(int w, int h, int power)
>> {
>>       double e = 1.0 + (0.3 * power);
>>       int x;
>>       for (x = 0; x < w; x++)
>>           for (int y = 0; y < h; y++)
>>               if (x + y != 0) {
>>                   double d = pow(sqrt(double(x * x + y * y)), e);
>>                   uwetable[x + y * w] = 1.0 / d;
>>               } else {
>>                   uwetable[x + y * w] = 1.0;
>>               }
>>
>>       for (x = 1; x < w - 1; x++)
>>           for (int y = 1; y < h - 1; y++) {
>>               double weightsum = 0;
>>               for (int bx = 0; bx < w; bx++) {
>>                   weightsum += uwetable[abs(bx - x) + y * w];
>>                   weightsum += uwetable[abs(bx - x) + abs(h - 1 - y) * w];
>>               }
>>               for (int by = 1; by < h - 1; by++) {
>>                   weightsum += uwetable[x + abs(by - y) * w];
>>                   weightsum += uwetable[abs(w - 1 - x) + abs(by - y) * w];
>>               }
>>               uweweightsum[y * w + x] = weightsum;
>>           }
>> }
>>
>> // apply filter
>> void TimgFilterLogoaway::Tplane::uwe(const TlogoawaySettings *cfg)
>> {
>>       if (!uwetable) {
>>           uwetable = (double*)aligned_malloc(w * h * sizeof(double));
>>           uweweightsum = (double*)aligned_malloc(w * h * sizeof(double));
>>           calcUweWeightTable(w, h, cfg->blur);
>>       }
>>
>>       for (int x = 1; x < w - 1; x++)
>>           for (int y = 1; y < h - 1; y++) {
>>               double r = 0;
>>               const unsigned char *lineN = bordn, *lineS = bords;
>>               for (int bx = 0; bx < w; bx++) {
>>                   r += lineN[bx] * uwetable[abs(bx - x) + y * w];
>>                   r += lineS[bx] * uwetable[abs(bx - x) + abs(h - 1 - y)
>> * w];
>>               }
>>               const unsigned char *lineW = bordw, *lineE = borde;
>>               for (int by = 1; by < h - 1; by++) {
>>                   r += lineW[by] * uwetable[x + abs(by - y) * w];
>>                   r += lineE[by] * uwetable[abs(w - 1 - x) + abs(by - y)
>> * w];
>>               }
>>               logotempdata[y * logotempstride + x] = uint8_t(r /
>> uweweightsum[y * w + x]);
>>           }
>>
>> }
>>
>>
>> Regards,
>> Uwe
>>
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>>
> Thanks,
> Kyle
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