Transcoding your textures to .rat files. Check http://scripts.wesleyelfring.nl/textures-to-rat/

Textures 2 Rat.py

import os
import glob
import subprocess

def we_startConversion():
    #Double check overwrite
    if hou.pwd().parm("cbOverwrite").eval() == 1:
        if hou.ui.displayMessage("Are you sure you want to overwrite RAT files?", buttons=("Yes", "No")) == 1:
            hou.pwd().parm("cbOverwrite").set(0)

    doOverwrite = hou.pwd().parm("cbOverwrite").eval()
    doWholeDir = hou.pwd().parm("cbWholeDir").eval()

    if doWholeDir == 0:
        #If the user only selected the one file
        outputDir = os.path.dirname(os.path.realpath(hou.pwd().parm("firstImage").eval()))
        fileName = os.path.splitext(os.path.realpath(hou.pwd().parm("firstImage").eval()))[0]

        if os.path.exists(fileName + ".rat"):
            if doOverwrite == 1:
                subprocess.call("iconvert \"" + os.path.realpath(hou.pwd().parm("firstImage").eval()) + "\" \"" + fileName + ".rat\"", shell=True)
        else:
            subprocess.call("iconvert \"" + os.path.realpath(hou.pwd().parm("firstImage").eval()) + "\" \"" + fileName + ".rat\"", shell=True)

        hou.ui.displayMessage("Conversion complete", buttons=("Ok",))
    else:
        #If the user selected the whole dir
        #Setup file names to convert
        outputDir = os.path.dirname(os.path.realpath(hou.pwd().parm("firstImage").eval()))
        types = ('*.pic', '*.pic.gz', '*.pic.Z', '*.gif', '*.jpg', '*.png', '*.tiff', '*.tif', '*.tga', '*.jpeg')
        files_grabbed = []
        for files in types:
            files_grabbed.extend(glob.glob(outputDir + os.sep + files))
        
        #Setup long operation 
        num_tasks = len(files_grabbed)       
        with hou.InterruptableOperation(
                "Converting images", open_interrupt_dialog=True) as operation:
            i = 0
            for image in files_grabbed:
                fileName = os.path.splitext(os.path.realpath(image))[0]
                print "iconvert \"" + image + "\" \"" + fileName + ".rat\""
                if os.path.exists(fileName + ".rat"):
                    if doOverwrite == 1:
                        subprocess.call("iconvert \"" + image + "\" \"" + fileName + ".rat\"", shell=True)
                else:
                    subprocess.call("iconvert \"" + image + "\" \"" + fileName + ".rat\"", shell=True)

                i = i + 1
                # Update operation progress.
                percent = float(i) / float(num_tasks)
                operation.updateProgress(percent)

        hou.ui.displayMessage("Conversion complete", buttons=("Ok",))