To convert a color image to black and white in Photoshop 7, you can use the Grayscale mode. To do this, go to the Image menu, choose Mode, and then choose Grayscale. Photoshop will ask if you want to discard the color information - click the Discard button. Another method is to use the Black & White adjustment layer. To do this, go to the Layer menu, choose New Adjustment Layer, and then choose Black & White. In the New Layer dialog box, type a name for the adjustment layer and then click OK. Photoshop will apply a default grayscale conversion to your image, which you can fine-tune in the Properties panel.