Transparent color range threshold

WTSupported in traditional Synergy on Windows




The SYN_TRANSPARENCY_THRESHOLD environment variable specifies a value that can be added to or subtracted from each RGB component of the transparent color to constitute an acceptable transparency range. It is ignored on Windows 8 and higher.


The threshold above or below each RGB component of the transparent color to accept as within the transparency range. This value must be in hexadecimal notation, preceded by “0x”, as follows:



This environment variable is primarily useful with JPEG images. Because JPEGs use a lossy compression algorithm, a pixel will not necessarily be returned in exactly the same color as it started out. Defining a transparency threshold can help eliminate transparency problems. For example, on a white background, a threshold of 0x10 can avoid white‑looking blotches in the background. With the following settings


Synergy/DE will accept colors as dark as 0xEF,0xEF,0xEF as transparent, which works well for JPEGs with a white background.

For non‑JPEG images, a threshold is typically not needed, unless you are not certain about the exact background color (for instance, when images are scanned in or from a third‑party source).

Setting location

The environment or the [synergy], [dbr], or [myprog] section of synergy.ini (where myprog is any .dbr file).

Used by

UI Toolkit, Composer, Synergy Windows printing API.


In the synergy.ini file,