The use of a texture operator is to help segmentation. You cannot just apply a texture operator on your image.
Texture:input:1, Texture:input:2, Texture:input:3, etc. are the spectral bands from the input image and IMAGINE Objective automatically identifies them.
The Segmentation Variable parameter on the Texture Properties tab is asking for the segmentation image.
You can create this segmentation variable image using IMAGINE’s Image Segmentation tool (Raster tab > Classification group > Unsupervised menu > Image Segmentation).
The output from the Image Segmentation tool is a thematic classified image.
The Segmentation variable defined in the Texture pixel cue properties must be different from the variable on which the cue is defined.