Struct CTCLabelDecode 

pub struct CTCLabelDecode { /* private fields */ }

A decoder for CTC (Connectionist Temporal Classification) based text recognition models.

This struct extends BaseRecLabelDecode to provide specialized decoding for CTC models, which include a blank token that needs to be handled specially during decoding.

Fields

• base - The base decoder that handles character mapping and basic decoding operations
• blank_index - The index of the blank token in the character vocabulary

Implementations

impl CTCLabelDecode

pub fn new(character_list: Option<&str>, use_space_char: bool) -> CTCLabelDecode

Creates a new CTCLabelDecode instance.

Arguments

• character_list - An optional string containing the character vocabulary. If None, a default alphanumeric character set is used.
• use_space_char - Whether to include a space character in the vocabulary.

Returns

A new CTCLabelDecode instance.

pub fn from_string_list( character_list: Option<&[String]>, use_space_char: bool, has_explicit_blank: bool, ) -> CTCLabelDecode

Creates a new CTCLabelDecode instance from a list of strings.

Arguments

• character_list - An optional slice of strings containing the character vocabulary. Only the first character of each string is used. If None, a default alphanumeric character set is used.
• use_space_char - Whether to include a space character in the vocabulary.
• has_explicit_blank - Whether the character list already includes a blank token.

Returns

A new CTCLabelDecode instance.

pub fn get_blank_index(&self) -> usize

Gets the index of the blank token.

Returns

The index of the blank token.

pub fn get_character_list(&self) -> &[char]

Gets the character list used by this decoder.

Returns

A slice containing the characters in the vocabulary.

pub fn get_character_count(&self) -> usize

Gets the number of characters in the vocabulary.

Returns

The number of characters in the vocabulary.

pub fn apply_with_positions( &self, pred: &ArrayBase<OwnedRepr<f32>, Dim<[usize; 3]>>, ) -> (Vec<String>, Vec<f32>, Vec<Vec<f32>>, Vec<Vec<usize>>, Vec<usize>)

Applies the CTC decoder to a tensor of model predictions with character position tracking.

This method handles the special requirements of CTC decoding and additionally tracks the timestep positions of each character for word box generation.

Arguments

• pred - A 3D tensor containing the model predictions.

Returns

A tuple containing:

• A vector of decoded text strings
• A vector of confidence scores for each text string
• A vector of character positions (normalized 0.0-1.0) for each text string
• A vector of column indices for each character in each text string
• A vector of sequence lengths (total columns) for each text string

pub fn apply( &self, pred: &ArrayBase<OwnedRepr<f32>, Dim<[usize; 3]>>, ) -> (Vec<String>, Vec<f32>)

Applies the CTC decoder to a tensor of model predictions.

This method handles the special requirements of CTC decoding:

1. Removing blank tokens
2. Removing consecutive duplicate characters
3. Converting indices to characters
4. Calculating confidence scores

Arguments

• pred - A 3D tensor containing the model predictions.

Returns

A tuple containing:

• A vector of decoded text strings
• A vector of confidence scores for each text string

Trait Implementations

impl Debug for CTCLabelDecode

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.