HOW TO: Convert a Transparent Image to a Non-transparent Format (e.g. PNG -> JPG)

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While some posts in this topic are more current, this topic was posted before the current version of LEADTOOLS was released and may no longer be applicable.

#1 Posted : Wednesday, January 6, 2010 11:54:07 AM(UTC)

GregR

Groups: Registered, Tech Support, Administrators
Posts: 764

A common need is to convert an image with transparency (such as a PNG) to a format that does not have transparency (such as JPEG). With LEADTOOLS, if you do a simple load and save, you will lose the alpha channel and the image will not look exactly the same. Therefore you must make a background image (usually just a solid color) and blend the alpha channel and base image together with the FeatherAlphaBlendCommand. This C# 2005 examples uses the .NET 16.5 interface to convert a transparent PNG file to a JPEG so that it will have the same look and feel as if it were displayed in Windows Picture and Fax Viewer (white background).

File Attachment(s):

NET - v16 - PNG to JPEG FeatherAlphaBlend.zip (15kb) downloaded 382 time(s).


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#2 Posted : Monday, August 20, 2012 5:22:15 AM(UTC)

Walter

Groups: Tech Support
Posts: 366

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Was thanked: 4 time(s) in 4 post(s)

This project has been updated for use with LEADTOOLS v17.5 and Visual Studio 2010.

File Attachment(s):

NET - v17.5 - PNG to JPEG FeatherAlphaBlend.zip (125kb) downloaded 330 time(s).

Walter Bates
Senior Support Engineer
LEAD Technologies, Inc.

#3 Posted : Sunday, June 23, 2013 10:45:53 PM(UTC)

Tamer_Irdais

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Posts: 3,022

Was thanked: 2 time(s) in 2 post(s)

Using an additional byte for each pixel to store an alpha mask (alpha channel) is a very common approach for representing transparency.
Many applications, both based on LEADTOOLS and non-LEAD imaging engines, support it in a uniform manner. Attached screenshot shows how MS Excel displays a 32-bit PNG file that has an alpha channel when that image is simply inserted into the sheet.

Guest attached the following image(s):

#4 Posted : Thursday, June 14, 2018 4:54:21 PM(UTC)

Walter

Groups: Tech Support
Posts: 366

Thanks: 1 times
Was thanked: 4 time(s) in 4 post(s)

Attached is an updated project that can target LEADTOOLS versions 16.5, 17.5, 18, 19, and/or 20. You can use the configuration for whichever version of LEADTOOLS you have on your machine.

To run this project, please extract it to the following directory:
C:\LEADTOOLS <version>\Examples\posts\t8052

File Attachment(s):

NET - PNG to JPEG FeatherAlphaBlend.zip (38kb) downloaded 305 time(s).

Walter Bates
Senior Support Engineer
LEAD Technologies, Inc.

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