If here is an image on my T-shirt, like how polo T-shirts has the image of a horse, but the image is not clear and only shaded in black, can one perform Salah while wearing this T-shirt?
الجواب حامدا و مصلیا
If the image is not clear, just as was mentioned by the questioner, then it is permissible to perform Salah in this T-shirt, otherwise it is disliked and should be avoided.