Load and Save Images - Python

This tutorial shows how to load and save an image file in a Python console application that uses the RasterCodecs and RasterImage classes.

Required Knowledge

Get familiar with the basic steps of creating a project by reviewing the Add References and Set a License tutorial, before working on the Load and Save Images - Python tutorial.

Create the Project and Add LEADTOOLS References

Start with a copy of the project created in this project: * Add References and Set a License for Python

If you do not have that project, follow the steps in the relevant tutorial to create it.

This tutorial requires the following DLLs:

• Leadtools.dll
• Leadtools.Codecs.dll

For a complete list of which Codec DLLs are required for specific formats, refer to File Format Support.

Set the License File

The License unlocks the features needed for the project. It must be set before any toolkit function is called. For details, including tutorials for different platforms, refer to Setting a Runtime License.

There are two types of runtime licenses:

• Evaluation license, obtained at the time the evaluation toolkit is downloaded. It allows the toolkit to be evaluated.
• Deployment license. If a Deployment license file and developer key are required, refer to Obtaining a License.

Add the Load Image Code

With the project created, the references added, and the license set, coding can begin.

In the Solution Explorer, open Project-Name.pyand place the following references below the "Add references to LEADTOOLS" comment

from leadtools import LibraryLoader 
LibraryLoader.add_reference("Leadtools") 
from Leadtools import * 
LibraryLoader.add_reference("Leadtools.Codecs") 
from Leadtools.Codecs import * 
 
from System.IO import * 

In the Python file add a new method called load_image(filename), and call it in the main method after the Support.set_license method. This tutorial uses the following test image C:\LEADTOOLS23\Resources\Images\image1.cmp

def main(): 
    Support.set_license(os.path.join(DemosTools.get_root(), "C:/LEADTOOLS23/Support/Common/License")) 
 
    image = load_image(r"C:\LEADTOOLS23\Resources\Images\image1.cmp") 
     

Add the below code to load the image, this will return a RasterImage:

def load_image(filename): 
 
    codecs = RasterCodecs() 
 
    # If Wanting to load from memory 
    # byte = File.ReadAllBytes(filename) 
    # ms = MemoryStream(byte) 
    # ms.Position = 0 
    # return codecs.Load(filename) 
 
    return codecs.Load(filename) 

Note: LEADTOOLS supports loading from memory streams. The commented out code above shows one way to load a stream into a RasterImage object.

Add the Save Image Code

In the Project-Name.py file, add a new method named save_image(image, output_filename)

def main(): 
    Support.set_license(os.path.join(DemosTools.get_root(), "C:/LEADTOOLS23/Support/Common/License")) 
 
    image = load_image(r"C:\LEADTOOLS23\Resources\Images\image1.cmp") 
    save_image(image, r"C:\LEADTOOLS23\Resources\Images\output.jpg") 

Add the below code to export the image as JPEG to the following file path: C:\LEADTOOLS23\Resources\Images\output.jpg

def save_image(image, output_filename): 
     
    codecs = RasterCodecs() 
   
    # If wanting to save to memory 
    # ms = MemoryStream() 
    # codecs.Save(image, ms, RasterImageFormat.Jpeg, 0) 
     
    codecs.Save(image, output_filename, RasterImageFormat.Jpeg, 0) 

Note: LEADTOOLS also supports saving to memory streams. The commented out code above shows how to save to a stream from a RasterImage object.

Run the Project

Run the project by pressing F5, or by selecting Debug -> Start Debugging.

If the steps were followed correctly, the application runs and creates a new file in the output location specified in the save call.

Wrap-up

This tutorial showed how to use the RasterCodecs and RasterImage classes to load and save images in a Python console Application.

See Also

• LEADTOOLS RasterImage Documentation
• LEADTOOLS RasterCodecs Documentation
• LEADTOOLS SDK Download