Field guide

How much of each photo a layout keeps

When a photo fills a cell of a different shape, some of it is cut off. The kept share is the part of the photo's own area that survives into the cell — the number shown on every cell and every suggestion here.

It needs only two shapes. The best a cell can do is the narrower aspect divided by the wider one: a photo wider than its cell loses its sides, a taller one loses top and bottom, and the share kept is the ratio of the two shapes.

Worked: a 3:2 landscape (1.5) in a square cell (1.0) keeps 1.0 ÷ 1.5 = 67%. A 4:3 landscape in the same square keeps 75%.

Worked: in a 4:5 portrait cell (0.8), a 3:4 portrait photo (0.75) keeps 0.75 ÷ 0.8 = 94%, but a 4:3 landscape (1.33) keeps only 0.8 ÷ 1.33 = 60%. Matching orientation matters more than anything else.

Worked: a 3:4 portrait in a 16:9 landscape cell (1.78) keeps 0.75 ÷ 1.78 = 42% — less than half the picture. That is why suggestions pair portraits with tall cells whenever the layout has them.

Those figures are the best case, at zoom 1 with the window centred. Zooming in on a cell keeps less, and the cell's readout drops as you do.

Suggestions are ranked by the mean kept share across filled cells, minus 0.08 for each empty cell and 0.06 for each face a cell edge would cut when faces are known — a halved head costs more than a few points of share.

Photos are matched to cells to maximise the total: for up to twelve photos the best pairing of photos to cells is searched for; beyond that, photos are paired with cells by shape. “Keep my order” under the suggestions turns matching off when the sequence matters more.

The fit-every-photo mode on the 100 photo collage keeps 100% of every photo by not cropping at all: it packs whole photos in justified rows and reports the smallest one's print size instead.