Try this setting, and compression will not be done for files under "2048" bytes in size (the default value for minCompressionSize):
<!-- Define a non-SSL HTTP/1.1 Connector on port 8080 -->
<Connector port="8080" maxHttpHeaderSize="8192"
           maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
           enableLookups="false" redirectPort="8443" acceptCount="100"
           connectionTimeout="20000" disableUploadTimeout="true"
           compression="512" 
           compressableMimeType="application/octet-stream,application/x-java-serialized-object,application/x-www-form-urlencoded,text/css,text/html,text/javascript,text/plain,text/richtext,text/tab-separated-values,text/xml" />


Compression will not be done for files under 512bytes in size:
<!-- Define a non-SSL HTTP/1.1 Connector on port 8080 -->
<Connector port="8080" maxHttpHeaderSize="8192"
           maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
           enableLookups="false" redirectPort="8443" acceptCount="100"
           connectionTimeout="20000" disableUploadTimeout="true"
           compression="2048" compressionMinSize="512"
           compressableMimeType="application/octet-stream,application/x-java-serialized-object,application/x-www-form-urlencoded,text/css,text/html,text/javascript,text/plain,text/richtext,text/tab-separated-values,text/xml" />




Compression will not be done for files under 512bytes in size:
<!-- Define a non-SSL HTTP/1.1 Connector on port 8080 -->
<Connector port="8080" maxHttpHeaderSize="8192"
           maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
           enableLookups="false" redirectPort="8443" acceptCount="100"
           connectionTimeout="20000" disableUploadTimeout="true"
           compression="2" compressionMinSize="512"
           compressableMimeType="application/octet-stream,application/x-java-serialized-object,application/x-www-form-urlencoded,text/css,text/html,text/javascript,text/plain,text/richtext,text/tab-separated-values,text/xml" />