Pixels: the small pieces of a picture
A pixel, short for picture element, is one sample of color in a digital image. A small image is like a mosaic of colored tiles. Together the tiles make a picture.
The image’s resolution describes its pixel dimensions. An image 32 pixels wide and 16 pixels high contains 512 pixel positions. That does not tell you its exact file size: the format, color data, and compression matter too.
Image size and drawing size
A small image can be drawn larger on screen. Enlarging it does not create missing original detail. Depending on the renderer, the result may look blocky or smoothed.
Pliro’s logical coordinates describe positions in its scene. They are not necessarily the same as physical screen pixels. A preview can scale a logical scene to fit a window or device. Mouse positions and drawing positions should use the same scene coordinate system.
A paper experiment
Draw an eight-by-eight grid and color squares to make a turtle. Then draw each original square as a two-by-two group. Your enlarged picture has bigger squares but the same original pattern.
Images may also store alpha, information about transparency. Transparent parts can let the background show through. Transparency does not automatically decide whether game objects collide; collision rules use their own geometry.