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If you by pixels are referring to the photoreceptors (rods & cones), their density differs over the retina, and we can only see sharp images at high resolution in a small region of our eye (fovea). So the resolution varies over the retina. The image we actually see is also a continiously interpreted and updated, and the brain is very creative in this process by basically "filling in the blanks". We therefore don't see in pixels, and our resolution is influenced by (at least) light conditions, contrast, photoreceptor density, signal merging and interpretation of the visual signals by the visual cortex in the brain. However, our eye is also constantly scanning the visual field (see saccade), so even if the "static" visual resolution (when we focus constantly on a single point) is drastically different over the visual field, this does not match our visual perception.

If we focus at the resolution in terms of photoreceptor density (densities of rods/cones), this is drastically different over regions of the retina. For instance, Jonas et al. (1992) reports ~150,000 cones/mm2 close to the center of the fovea to 2500-6000 cones/mm2 towards the periphery. The approximate density of rods goes from 150,000 rods/mm2 to 30,000 in the periphery. Cone & rod diameter also differs over the retina, with larger diameters towards the retinal periphery, which relates to light sensitivity.

A nice summary of the flexibility and limitations of human vision can be seen in this xkcd comic (click for larger version): (from "xkcd: Our central visual field" at http://xkcd.com/1080/)

If you by pixels are referring to the photoreceptors (rods & cones), their density differs over the retina, and we can only see sharp images at high resolution in a small region of our eye (fovea). So the resolution varies over the retina. The image we actually see is also a continiously interpreted and updated, and the brain is very creative in this process by basically "filling in the blanks". We therefore don't see in pixels, and our resolution is influenced by (at least) light conditions, contrast, photoreceptor density, signal merging and interpretation of the visual signals by the visual cortex in the brain. However, our eye is also constantly scanning the visual field (see saccade), so even if the "static" visual resolution (when we focus constantly on a single point) is drastically different over the visual field, this does not match our visual perception. As a sidenote, saccades are possibly the fastest human motions, and can reach speeds well above 400°/s (Boghen et al, 1975) - wikipedia reports 900°/s but without a clear reference - and takes place several times per second.

If we focus at the resolution in terms of photoreceptor density (densities of rods/cones), this is drastically different over regions of the retina. For instance, Jonas et al. (1992) reports ~150,000 cones/mm² close to the center of the fovea to 2500-6000 cones/mm² towards the periphery. The approximate density of rods goes from 150,000 rods/mm² to 30,000 in the periphery. Cone & rod diameter also differs over the retina, with larger diameters towards the retinal periphery, which relates to light sensitivity.

A nice summary of the flexibility and limitations of human vision can be seen in this xkcd comic (click for larger version): (from "xkcd: Our central visual field" at http://xkcd.com/1080/)

If you by pixels are referring to the photoreceptors (rods & cones), their density differs over the retina, and we can only see sharp images at high resolution in a small region of our eye (fovea). So the resolution varies over the retina. The image we actually see is also a continiously interpreted and updated, and the brain is very creative in this process by basically "filling in the blanks". We therefore don't see in pixels, and our resolution is influenced by (at least) light conditions, contrast, photoreceptor density, signal merging and interpretation of the visual signals by the visual cortex in the brain.

If we focus at the resolution in terms of photoreceptor density (densities of rods/cones), this is drastically different over regions of the retina. For instance, Jonas et al. (1992) reports ~150,000 cones/mm2 close to the center of the fovea to 2500-6000 cones/mm2 towards the periphery. The approximate density of rods goes from 150,000 rods/mm2 to 30,000 in the periphery. Cone & rod diameter also differs over the retina, with larger diameters towards the retinal periphery, which relates to light sensitivity.

A nice summary of the flexibility and limitations of human vision can be seen in this xkcd comic (click for larger version): (from "xkcd: Our central visual field" at http://xkcd.com/1080/)

If you by pixels are referring to the photoreceptors (rods & cones), their density differs over the retina, and we can only see sharp images at high resolution in a small region of our eye (fovea). So the resolution varies over the retina. The image we actually see is also a continiously interpreted and updated, and the brain is very creative in this process by basically "filling in the blanks". We therefore don't see in pixels, and our resolution is influenced by (at least) light conditions, contrast, photoreceptor density, signal merging and interpretation of the visual signals by the visual cortex in the brain. However, our eye is also constantly scanning the visual field (see saccade), so even if the "static" visual resolution (when we focus constantly on a single point) is drastically different over the visual field, this does not match our visual perception.

If we focus at the resolution in terms of photoreceptor density (densities of rods/cones), this is drastically different over regions of the retina. For instance, Jonas et al. (1992) reports ~150,000 cones/mm2 close to the center of the fovea to 2500-6000 cones/mm2 towards the periphery. The approximate density of rods goes from 150,000 rods/mm2 to 30,000 in the periphery. Cone & rod diameter also differs over the retina, with larger diameters towards the retinal periphery, which relates to light sensitivity.

A nice summary of the flexibility and limitations of human vision can be seen in this xkcd comic (click for larger version): (from "xkcd: Our central visual field" at http://xkcd.com/1080/)

If you by pixels are referring to the photoreceptors (rods & cones), their density differs over the retina, and we can only see sharp images at high resolution in a small region of our eye (fovea). So the resolution varies over the retina. The image we actually see is also a continiously interpreted and updated, and the brain is very creative in this process by basically "filling in the blanks". We therefore don't see in pixels, and our resolution is influenced by (at least) photoreceptor density, signal merging and interpretation of the visual signals by the visual cortex in the brain.

If we focus at the resolution in terms of photoreceptor density (densities of rods/cones), this is drastically different over regions of the retina. For instance, Jonas et al. (1992) reports ~150,000 cones/mm2 close to the center of the fovea to 2500-6000 cones/mm2 towards the periphery. The approximate density of rods goes from 150,000 rods/mm2 to 30,000 in the periphery. Cone & rod diameter also differs over the retina, with larger diameters towards the retinal periphery, which relates to light sensitivity.

A nice summary of the flexibility and limitations of human vision can be seen in this xkcd comic (click for larger version): (from "xkcd: Our central visual field" at http://xkcd.com/1080/)

If you by pixels are referring to the photoreceptors (rods & cones), their density differs over the retina, and we can only see sharp images at high resolution in a small region of our eye (fovea). So the resolution varies over the retina. The image we actually see is also a continiously interpreted and updated, and the brain is very creative in this process by basically "filling in the blanks". We therefore don't see in pixels, and our resolution is influenced by (at least) light conditions, contrast, photoreceptor density, signal merging and interpretation of the visual signals by the visual cortex in the brain.

If we focus at the resolution in terms of photoreceptor density (densities of rods/cones), this is drastically different over regions of the retina. For instance, Jonas et al. (1992) reports ~150,000 cones/mm2 close to the center of the fovea to 2500-6000 cones/mm2 towards the periphery. The approximate density of rods goes from 150,000 rods/mm2 to 30,000 in the periphery. Cone & rod diameter also differs over the retina, with larger diameters towards the retinal periphery, which relates to light sensitivity.

A nice summary of the flexibility and limitations of human vision can be seen in this xkcd comic (click for larger version): (from "xkcd: Our central visual field" at http://xkcd.com/1080/)