readBarcode

R2026b

Detect and decode 1-D or 2-D barcode in image

Syntax

msg = readBarcode(I)

msg = readBarcode(I,roi)

msg = readBarcode(___,format)

msg = readBarcode(___,Name=Value)

[msg,detectedFormat,loc] = readBarcode(___)

Description

msg = readBarcode(I) detects and decodes a 1-D or 2-D barcode in the input image and returns the message associated with that barcode.

If the input image contains multiple barcodes, the readBarcode function decodes only the first barcode detected.

msg = readBarcode(I,roi) specifies a rectangular region of interest (ROI) to reduce the area in which the function searches for a barcode. The ROI must be fully contained in the input image.

msg = readBarcode(___,format) specifies barcode formats to reduce the types of barcodes for which the function searches. Specify this argument in addition to any of the input argument combinations in previous syntaxes.

msg = readBarcode(___,Name=Value) specifies options using a name-value argument in addition to any combination of arguments from previous syntaxes. For example, GaussianSigma=1.0 applies a 2-D Gaussian filter to the input image with a standard deviation set to 1.

[msg,detectedFormat,loc] = readBarcode(___) additionally returns the format, detectedFormat, and location, loc, of the detected barcode.

Examples

Detect and Decode 1-D Barcode

Read an image containing a barcode into the workspace.

I = imread("barcode1D.jpg");

Detect the barcode and decode its message.

msg = readBarcode(I);

Display the decoded barcode message.

disp("Decoded barcode message: " + msg)

Decoded barcode message: 1234567890128

Search Image for 1-D Barcode

Read an image containing a barcode into the workspace.

I = imread("barcode1D.jpg");

Search the image for a 1-D barcode, returning its message, format, and location.

[msg,detectedFormat,loc] = readBarcode(I,'1D');

Display the detected barcode format.

disp("Barcode format: " + detectedFormat)

Barcode format: EAN-13

Annotate the image with the decoded barcode message.

xyBegin = loc(1,:);
Imsg = insertText(I,xyBegin,msg,'BoxOpacity',1,'FontSize',30);

Insert a line to show the scan row.

imSize = size(Imsg);
Imsg = insertShape(Imsg,'Line',[1 xyBegin(2) imSize(2) xyBegin(2)],'LineWidth',5);

Display the image.

imshow(Imsg)

Read a QR Barcode

Read an image containing a barcode.

I = imread("barcodeQR.jpg");

Define the ROI in the image that contains the barcode.

roi = [470, 300, 720, 620];

Search for a QR barcode within the ROI.

[msg,~,loc] = readBarcode(I,roi,"QR-CODE");

Annotate the image with the decoded message from the detected barcode.

xyText =  loc(2,:)/4;
Imsg = insertText(I,xyText,msg,"BoxOpacity",1,"FontSize",35);

Insert red circles onto the image to indicate the finder pattern locations.

Imsg = insertShape(Imsg, "FilledCircle", [loc, ...
     repmat(10, length(loc), 1)],"ShapeColor","red","Opacity",1);

Display the image.

imshow(Imsg)

Input Arguments

I — Input image

truecolor image | grayscale image

Input image, specified as a truecolor or grayscale image.

roi — Region of interest

four-element vector

Region of interest, specified as a four-element row vector of the form [x, y, width, height]. The rectangular ROI must be fully contained in the input image. [x,y] specifies the starting point for the ROI relative to the upper-left corner of the image.

If an image contains multiple barcodes, specifying an ROI can help the function detect a particular barcode. For more information, see Read Barcodes in Image.

format — Barcode format

'1D' | '2D' | one or more valid barcode formats

Barcode format, specified as one of these options. The table lists valid barcode formats.

• 'all' — Use this option to specify all valid barcode formats. If you do not specify a format, the function uses this option.

• '1D' — Use this option to specify all valid 1-D barcode formats.

• '2D' — Use this option to specify all valid 2-D barcode formats.

• A character vector or string scalar of a valid format — Use this option to specify one barcode format.

• A cell array of character vectors or vector of strings of valid formats — Use this option to specify multiple barcode formats. The function prioritizes its search for specific barcode formats based on the order of the elements in this array.

Specifying a format can reduce the run time of the function by restricting the barcode search.

1-D Formats	2-D Formats
UPC-A	QR-CODE
UPC-E	DATA-MATRIX
EAN-8	AZTEC
EAN-13	PDF-417
CODE-39
CODE-93
CODE-128
CODABAR
ITF
RSS-14
RSS-EXPANDED

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: GaussianSigma=1.0 applies a 2-D Gaussian filter to the input image with a standard deviation set to 1.

GaussianSigma — Standard deviation for 2-D Gaussian filtering

0 (default) | nonnegative scalar

Standard deviation for 2-D Gaussian filtering, specified as a nonnegative scalar. This name-value argument applies only when set the barcode format to "DATA-MATRIX". When you set the value to a nonzero scalar, the function applies a 2-D Gaussian filter to the input image as a preprocessing step. When you set the value to 0, the function does not apply Gaussian filtering.

Smoothing can improve detection for barcodes with circular markers, such as those produced by dot peen marking (DPM). Typical values range from 1 to 2. Determine the optimal value empirically for your application.

Output Arguments

msg — Barcode message

string scalar

Barcode message, returned as a string scalar.

detectedFormat — Detected barcode format

string scalar

Detected barcode format, returned as a string scalar of one of the formats in this table.

1-D Formats	2-D Formats
UPC-A	QR-CODE
UPC-E	DATA-MATRIX
EAN-8	AZTEC
EAN-13	PDF-417
CODE-39
CODE-93
CODE-128
CODABAR
ITF
RSS-14
RSS-EXPANDED

loc — Location of barcode

M-by-2 matrix | 2-by-2 matrix

Location of barcode, returned as an M-by-2 matrix for 2-D barcodes or a 2-by-2 matrix for 1-D barcodes. The matrix elements represent finder pattern locations.

Barcode	loc Value	Finder Pattern Locations
2-D	M-by-2 matrix. M represents the number of [x, y] locations of finder patterns.
1-D	2-by-2 matrix of the form [x1, y1;x2, y2], where each row represents the location of a finder pattern.

Tips

• The function detects only clearly visible barcodes.

• Specifying a format can reduce the run time of the function by restricting the barcode search.

• For noisy images with unclear barcodes, use image preprocessing functions, such as imsharpen.

• The function detects only horizontally or vertically aligned barcodes. Use imrotate to correct poorly aligned barcodes.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• Input argument format must be specified as a string scalar, character vector, or cell array of character vectors. String arrays are not supported.

You can also generate optimized C/C++ code using Embedded Coder™.

GPU Code Generation

Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Refer to the usage notes and limitations in the C/C++ Code Generation section. The same usage notes and limitations apply to GPU code generation.

Version History

Introduced in R2020a

R2026b: Added GaussianSigma name-value argument

You can now specify the GaussianSigma name-value argument to apply 2-D Gaussian filtering as a preprocessing step when reading "DATA-MATRIX" barcodes.

R2024b: Generate optimized C/C++ code using Embedded Coder

Starting in R2024b, you can generate optimized C/C++ code using Embedded Coder.