Reference cards at an exact size
A test card only works when the pixels arrive untouched. Set the width and height to the native resolution of the display, capture card, or encoder you are checking, pick a pattern, and export it without an intermediate resize.
SMPTE bars and PLUGE
The SMPTE card packs three measurements into one frame. The top two thirds hold seven 75% saturation bars in descending luminance order: white, yellow, cyan, green, magenta, red, blue. The narrow strip below reverses the chroma order for phase checks. The bottom row carries the -I and +Q patches, a 100% white reference, and PLUGE.
PLUGE is the useful part for a monitor. Three near-black bars sit at roughly 4 IRE below black, at black, and 4 IRE above it. Correct brightness makes the rightmost bar just visible while the leftmost one disappears into the surrounding black.
Grayscale steps vs the ramp
The staircase splits the frame into even luminance steps, from 0 to 255, with each value printed on its step. Read it from both ends: if the darkest two steps look identical, blacks are crushed; if the brightest two merge, whites are clipped.
The ramp answers a different question. It runs the same range continuously, so contouring reveals bit depth rather than clipping. A clean 8-bit ramp shows faint even bands. Wide, uneven, or colored bands usually mean the signal path dropped to 6-bit or applied dithering of its own.
Geometry: grid, checkerboard, line pairs
The linearity grid draws even crosshatch lines, corner-to-corner diagonals, and a circle inscribed in the shorter axis. The circle is the fastest aspect check: it goes oval the moment something stretches the frame.
The checkerboard exposes scaler behavior. At 1px cells it doubles as the classic subpixel and sharpening test; at 8px or larger it becomes the transparency grid used in image editors.
The line-pair wedge draws vertical and horizontal groups at 1px, 2px, 3px, 4px, 6px, and 8px pitch. Rendered 1:1 the finest group stays crisp. Any softness, shimmer, or moiré there means the image is being resampled somewhere in the chain.
Overlays
The resolution stamp writes the pixel dimensions into the corner so a card cannot be confused with a rescaled copy of itself. The safe-area overlay adds dashed rectangles at 5% and 10% inset, matching the action-safe and title-safe regions used for broadcast layout, plus a centre cross.
PNG over JPEG
Export as PNG unless the target only accepts a lossy format. JPEG chroma subsampling averages color across pixel pairs, which softens the vertical edges between saturated bars, and its quantization introduces ringing exactly where the wedge is meant to be sharp. WebP in lossy mode has the same problem. The bars will still look like bars, but they stop being a measurement.