Every card that comes to CALIBRE is photographed front and back – lit from four directions, and under UV light – and measured: over 800 measurements covering every corner (each at 91 points), every edge, the border on all four sides and the whole surface. A person also checks by hand that it’s genuine. Here’s what each step does.
The principle
Every physical object has measurable properties. A trading card is no exception. Its borders, its corners, its edges and its surface can all be measured. Take enough of these measurements with enough precision, and you can describe the card’s condition in numbers instead of opinions.
CALIBRE’s grading approach is built around this idea. Rather than looking at a card and forming a judgement about it, CALIBRE measures the card and reports the results. The grade emerges from the data, not from interpretation. The results go into your report, so you can see how the grade was reached.
Authenticity – checked by hand
Before any card is graded, a person checks by hand, under calibrated lighting, that it is genuine. Fakes are common and getting better, and a condition grade on a fake card is worthless – so this check happens on every card. A card that isn’t genuine doesn’t get a grade.
Photometric stereo – surface reconstruction
If you photograph a card under flat overhead lighting, the result is a picture of the card’s artwork and text. If you photograph the same card under light coming from one side, the shadows cast by every tiny scratch, dent, and print defect become visible.
Photometric stereo takes this principle further. CALIBRE photographs each side of the card with light coming from four different directions – left, right, top and bottom – at several brightness levels. By comparing how the shadows change between these photos, our software picks out scratches, dents and print marks that a single flat photo would miss.
Any marks it finds are shown in your report. At CALIBRE’s imaging resolution of eighty pixels per millimetre, surface features as small as a tenth of a millimetre are captured precisely.
Centering – measuring the border
Cards are cut from big printed sheets, and the cut is rarely perfect. If the picture sits closer to one side, the borders aren’t even – and that can cost a card its top grade.
CALIBRE measures the border on all four sides, front and back, and works out how evenly the picture sits: left against right, and top against bottom.
Your report shows the split for both faces as a percentage. 50/50 is perfect; the further from that, the more off-centre the print.
Ultraviolet – a second look at the edges
Most people have seen the effect of UV light in clubs and at airports. Certain materials – banknote security features, white shirts, bank security strips – glow under UV light because they contain chemicals that absorb ultraviolet wavelengths and re-emit them as visible light. This is called fluorescence.
Card stock, inks and coatings react to UV light too. As well as the normal photos, CALIBRE takes a photo of each side of the card under UV light.
Under UV, whitening along an edge can stand out more clearly than in normal light, so the UV photo helps the edge check. It is part of measuring condition – the authenticity check is done separately, by hand.
Corners – measured against the ideal curve
Card corners are cut to a standard curve. CALIBRE measures every corner, front and back, and compares it with that ideal curve.
Any rounding, softening or chip shows up as a difference from the curve, measured in millimetres.
Edges – dings and whitening
Each of the four edges, front and back, is checked for dings and whitening.
The same standards for every card
Every measurement is checked against a fixed standard: the number a card has to hit for each grade. The same standards apply to every card.
Your report shows the measurements behind your grade.
Putting it all together
The machine photographs the front of the card – lit from four directions, then under UV – and then the back gets exactly the same. A person checks by hand that the card is genuine before it is graded.
Over 800 measurements in total – 728 of them on the corners alone. The grade is worked out from those measurements by fixed rules, against the same standards. No interpretation. No judgement. No opinion.