1. A method, comprising: receiving, by a computing device, image data depicting a first financial document; determining, by the computing device, based on the received image data, a distance from an edge of the depicted first financial document to a feature of the depicted first financial document by selecting a starting point along the edge and comparing adjacent pixels in a specific direction until a change in brightness or color between two adjacent pixels exceeds a predetermined threshold; generating a first vector, the first vector including at least one vector component, the at least one vector component representing the distance; comparing, by the computing device, the generated first vector with a second vector, the second vector being associated with a second financial document; determining, by the computing device, a confidence score for the first financial document based on the comparison, the confidence score indicating a level of confidence that the first financial document is valid; selecting, by the computing device, a threshold based on a classification of a channel through which the image data associated with the first financial document is received, wherein channels are classified as one of a teller transactions channel, an ATM transactions channel, and a mobile deposit transactions channel, and channels of a same classification have a same threshold; and in response to determining that the confidence score exceeds the selected threshold, authorizing, by the computing device, a transaction involving the first financial document.