An electronic assembly comprising an electronic device that has a sensor and a display area that corresponds to the entire display or a portion of said entire display, the electronic assembly further comprising an accessory that comprises: a cover portion suitable for covering the display area of the electronic device wherein the cover portion comprises a first element that can be sensed by said sensor when the cover portion covers the display area and including: a transparent layer, a first layer disposed on one side of the transparent layer and having a plurality of first apertures; and a second layer disposed on the other side of the transparent layer and having a plurality of second apertures, each of the plurality of first apertures of the first layer corresponds to a respective one of the plurality of second apertures of the second layer, wherein the plurality of the first and second apertures (605, 606) with the transparent layer together form a plurality of light-transmitting areas, wherein the plurality of light-transmitting areas are arranged in an array having a light-transmitting area density, and configured for an image generated by the display area to be projected out of the cover portion to form a dotted character, a dotted symbol, or a dotted pattern, wherein the electronic device is configured to display the image as a high-resolution image in an area of the entire display not covered by the cover portion, and as a low-resolution image according to the light transmitting area density, in the display area covered by the cover portion. a cover portion suitable for covering the display area of the electronic device wherein the cover portion comprises a first element that can be sensed by said sensor when the cover portion covers the display area and including: a transparent layer, a first layer disposed on one side of the transparent layer and having a plurality of first apertures; and a second layer disposed on the other side of the transparent layer and having a plurality of second apertures, each of the plurality of first apertures of the first layer corresponds to a respective one of the plurality of second apertures of the second layer, wherein the plurality of the first and second apertures (605, 606) with the transparent layer together form a plurality of light-transmitting areas, wherein the plurality of light-transmitting areas are arranged in an array having a light-transmitting area density, and configured for an image generated by the display area to be projected out of the cover portion to form a dotted character, a dotted symbol, or a dotted pattern, wherein the electronic device is configured to display the image as a high-resolution image in an area of the entire display not covered by the cover portion, and as a low-resolution image according to the light transmitting area density, in the display area covered by the cover portion. a transparent layer, a first layer disposed on one side of the transparent layer and having a plurality of first apertures; and a second layer disposed on the other side of the transparent layer and having a plurality of second apertures, each of the plurality of first apertures of the first layer corresponds to a respective one of the plurality of second apertures of the second layer, wherein the plurality of the first and second apertures (605, 606) with the transparent layer together form a plurality of light-transmitting areas, wherein the plurality of light-transmitting areas are arranged in an array having a light-transmitting area density, and configured for an image generated by the display area to be projected out of the cover portion to form a dotted character, a dotted symbol, or a dotted pattern, wherein the electronic device is configured to display the image as a high-resolution image in an area of the entire display not covered by the cover portion, and as a low-resolution image according to the light transmitting area density, in the display area covered by the cover portion.