by John McLaren and Chris Cieslik
Answer: SEPIA FILTER
Problem: April Fool’s Day

Solvers are presented with four nonograms, where some rows have fractional values (always ×.5).

These are nonograms with three possible fill colors—white, black, and gray (clued by the flavortext—nothing is ever just black or white, and the puzzle’s title) with each gray square counted as 0.5.

Thus, a clue of 1.5 indicates three gray squares, and a clue of 3 could indicate three black squares or six gray squares.

Filling in the nonograms will reveal overlapping letters in pairs—one white, one black. Gray is the background color of each grid, and also the color where the white and black letters overlap. The black letters are the consecutive letters of the alphabet from K to Z.

Taking the white letters in that order yields ANS IS SEPIA FILTER.

The completed grids are presented below—the white letter is depicted in red, the black letter depicted in blue. Points where the letters overlap are in purple, and the background of gray has been turned white for clarity.

 1
4.5
1.5
6
1
0.5
2
2.5
0.5
1
1
0.5
4
5
0.5
0.5
1
0.5
1
0.5
1
3
2.5
1
4
3.5
4.5
5
1
4.52
0.5
4
4
1
0.5
1
1.5
0.5
1
0.5
1
1.5
2
0.5
3
0.5
0.5
2
1
1
1.5
1
1
2
1
2
1
1.5
1
4
3
1
4.5
6
0.5
1 2.5 1.5                
1 1 0.5 2 1 3 2                
1 1 1.5 1 1 1 1                
0.5 1.5 0.5 1 1                
1 1 1.5 4 1.5                
1 1 1.5 1 1 1 1.5                
1 1 1.5 1 1.5 1 1                
1.5 1 2.5 1 1.5 1 1                
1 1.5 0.5                
1.5 1 1 1 1 1 1.5 1                
1.5 1 1 1 1 1 1.5 1                
1.5 1 1 1 1 0.5 0.5 1                
1.5 1 1 1 1 1 1.5 1                
1.5 1 1 1 1 1 1.5 1                
1 0.5 2 1 1.5 1                
2.5 1 3 3 0.5                
 4.5
1
1
4
2
0.5
2
0.5
1
0.5
0.5
1
1
0.5
0.5
5
0.5
2.5
0.5
3.5
1
0.5
1
0.5
1
2
2
1
7
3.5
1
4
0.5
5
5
0.5
1
5
2
0.5
2
0.5
1
4
1
0.5
1
0.5
0.5
3.5
1
0.5
1
0.5
0.5
2
1.5
2
2.5
1
0.5
0.5
0.5
0.5
4
1.5
1.5
1
1.5
4
1
1
0.5
1
1
4.5
2
1.5
2
1 3 2                
1 1 1.5 1 3 0.5 1 1                
1 1 1.5 1 1 1.5 1 1                
1 1 1.5 1 1 0.5 1 1                
1 1 0.5 1 0.5 1 0.5 3 0.5 1 1                
1 1 0.5 1 0.5 1 1 1 1.5                
1 0.5 2 2                
2 1 0.5 1 1 1 3                
0.5 3 0.5                
1 1 1 2.5 1 1 1                
2 0.5 2 2.5 1 1 1                
1 1 1 4 1 0.5                
0.5 1 1 1 3 1 1                
1 1 1 4 1 0.5                
1 0.5 1 2.5 1 1 1                
0.5 1 1.5 1 2.5 1 1.5 1                
 4
2.5
0.5
4
5
0.5
1
4
0.5
0.5
0.5
1
1
1.5
1
0.5
0.5
0.5
1
0.5
2
1
2
1
0.5
1
0.5
1
1
0.5
7
1
0.5
1
1
4
2
0.5
1
4
1
5
4.5
4
2.5
0.5
1
0.5
0.5
2
2
1
1
0.5
4
0.5
0.5
1
1
1
1.5
1
1
1
0.5
1
0.5
1.5
1
1
1
1
1
0.5
1
1.5
2
1
1
2
0.5
0.5
1
2.5
1
4
2 2.5 1.5                
1.5 0.5 2 3 0.5 1                
1.5 1 1.5 1 0.5 1 2                
2.5 0.5 1 0.5 0.5 0.5 0.5                
2 1 1 1 0.5 2 0.5 0.5                
1.5 1 1 1 0.5 1 0.5 1 0.5                
2.5 0.5 1 0.5 1 2                
2.5 3 1.5 1 1.5 1                
2 1                
0.5 1 1 1 3 2 1                
0.5 1 1 1 2 1 1 1 0.5                
0.5 1 1.5 1 2 1 2                
0.5 1 1 0.5 1 3 2 1                
0.5 1 0.5 2 2.5 1 1 0.5                
0.5 1 1.5 0.5 1 0.5                
0.5 1 1.5 1 2.5 3 1                
 4.50.5
1
0.5
2
5
1
0.5
1
1
4
1
0.5
0.5
1
1
0.5
1
2.5
1
1
0.5
1
0.5
1
6
0.5
1
1
0.5
4
1.5
2
0.5
1
4
0.5
1
1.5
0.5
4.5
1
3
4
0.5
1
1
0.5
5
1
0.5
1
2
1.5
1.5
1
1
0.5
0.5
1
0.5
1
2
1
1
1
0.5
1.5
1
1
1
1
0.5
1
3.5
1
0.5
2
2
1
4
2.5 1                
0.5 3 2.5 3 0.5 1                
1 1.5 1 2 1.5 1                
0.5 0.5 1 2 1 0.5                
1 1.5 1 2 2.5                
1 0.5 1 0.5 1 2 0.5 1 0.5 0.5                
0.5 0.5 1 2 1 1 0.5                
1 4 2.5 5                
1.5 0.5 1.5 1                
1.5 1 1.5 1 1 1 1                
1.5 0.5 1 0.5 1 0.5 1.5 1                
1.5 1.5 1 0.5 1                
1.5 1 1 1 1 0.5 1                
1.5 1 1 1 1 1 1                
1.5 0.5 0.5 1 1 1                
3 1 1.5 5 0.5