Value, not color: the gray-scale photo test
The scrappy Nine Patch I started in March looked wrong on the design wall, which in this house is a flannel-backed tablecloth pinned to the hallway wall with thumbtacks. Every block was made from fabrics I liked, the colors went together, and yet the whole thing read as a flat, muddy field with no pattern in it at all. I moved blocks around for three evenings before I thought to take a photograph with the camera set to black and white.
The photo told the story in one glance. Of the eleven fabrics in the top, seven were almost the same middle gray. A rust, an olive, a dusty blue and a plum that look completely different in color are nearly identical in value, and value is what a Nine Patch needs to show its grid. The two lights I had chosen were also not that light; one of them, a tan with a small print, photographed darker than the dusty blue.
So I took the top apart at the sashing and swapped fabrics in about a third of the blocks. The replacements were a plain unbleached muslin for the lights and a near-black navy for the darks, both solids, both boring on their own. In the black and white photo the grid snapped into focus; in color it still has all the rust and olive and plum, but now you can see the pattern from across the room instead of a yard away.
A few other things I learned about fabric choices while I was at it. Cotton lawn is lovely to touch but too thin for piecing with quilting cotton; the darker seam allowances shadow through the light squares, so I pulled the one lawn print entirely. A linen and cotton blend frayed so badly at the raw edges that my quarter-inch seam became an eighth after handling. Shot cotton, with a different colored warp and weft, changes value depending on the light and was the hardest to place; I kept it only in the middle squares where it does not matter.
I now take a gray-scale photo of every pull of fabric before I cut, and I try to have a true light and a true dark in every block even if the middle is all scraps.