  Context. Accurate detections of frequent small-scale extreme ultraviolet
(EUV) brightenings are essential to the investigation of the physical processes
heating the corona. Aims. We detected small-scale brightenings, termed
campfires, using their morphological and intensity structures as observed in
coronal EUV imaging observations for statistical analysis. Methods. We applied
a method based on Zernike moments and a support vector machine classifier to
automatically identify and track campfires observed by Solar Orbiter/Extreme
Ultraviolet Imager (EUI) and SDO/AIA. Results. This method detected 8678
campfires (with length scales between 400 km and 4000 km) from a sequence of 50
High Resolution EUV telescope (HRIEUV) 174{\AA} images. From 21 near
co-temporal AIA images covering the same field of view as EUI, we found 1131
campfires, 58% of which were also detected in HRIEUV images. In contrast, about
16% of campfires recognized in HRIEUV were detected by AIA. We obtain a
campfire birthrate of 2*10-16m-2s-1. About 40% of campfires show a duration
longer than 5 s, having been observed in at least two HRIEUV images. We find
that 27% of campfires were found in coronal bright points and the remaining 73%
have occurred out of coronal bright points. We detected 23 EUI campfires with a
duration greater than 245 s. We found that about 80% of campfires are formed at
supergranular boundaries, and the features with the highest total intensities
are generated at network junctions and intense H I Lyman-{\alpha} emission
regions observed by EUI/HRILya. The probability distribution functions for the
total intensity, peak intensity, and projected area of campfires follow a power
law behavior with absolute indices between 2 and 3. This self-similar behavior
is a possible signature of self-organization, or even self-organized
criticality, in the campfire formation process.
