Then please follow the manual, take the cell from the notebook, paste it into the post mark it and use the "Code Sample" button:
Clear[normImage, formatImage]
normImage[ext_String, d__ (* path dirs *)] :=
formatImage[FileNameJoin[{d}], ext] /; StringLength[ext] > 0
formatImage[d_String, ext_String, big_Integer: 1076] :=
Module[{fN, p, pxy, ims, oo = 0},
If[! DirectoryQ[d],
Print[d, " is not a directory here. Bye."];
Return[$Failed]
];
SetDirectory[d];
Print["Directory set to \"", d, "\""];
fN = FileNames[StringJoin["*.", ext]];
If[ Length[fN] < 1,
Print["No files *.", ext, " found in directory ", d];
Return[$Failed]
];
For[o = 1, o <= Length[fN], ++o,
p = Import[fN[[o]], ext];
If[ImageQ[p],
pxy = Import[fN[[o]], "ImageSize"];
(* die groessere Dimension des Bildes wird auf big gesetzt,
die kleinere Dimentsion wird maßstabsgetreu angepaßt. *)
ims = If[pxy[[1]] > pxy[[2]],
{big, pxy[[2]] big/pxy[[1]]}, (* else *)
{pxy[[1]] big/pxy[[2]], big}
];
Export[fN[[o]], p, ImageSize -> ims];
oo++;
Print["Done: ", fN[[o]]], (* else *)
Print["File ", fN[[o]], " does not represent a picture."]
]
];
Print[" Done ", oo, " from ", Length[fN], " pictures given."]
] /; Positive[big] && StringLength[ext] > 0
Do the same with the theta
In[1]:= \[Theta] + \[Theta]
Out[1]= 2 \[Theta]
this is the official appearance of Theta in Mathematica, nothing wrong with it despite it does not look like a Theta.