Gonzaloacid escribió:1920x1080
esos números expresan un tamaño (un área), y no una resolución. 1920 son los pixel del lado mayor y 1080 los del lado menor.
la resolución en fotografía digital se expresa en pixel / pulgada, y en fotografía analógica el lineas por milímetro o más comunmente _pero de modo incorrecto (*)_, en pares de líneas por milímetro - line pairs per millimeter (lppmm o LP/mm). dejo el link para fotografía digital solamente porque, aparentemente, es lo que interesa en este grupo:
http://www.luminous-landscape.com/tutorials/understanding-series/und_resolution.shtml#need
"If you were to now change any one of the values for Width, Height or Resolution you would simultaneously change the other two. If for example you changed the Height to 6 inches then the Width would become 4 inches and the Resolution would become 360 ppi, as seen below.
This is because a digital image has no absolute size or resolution. All it has are a certain number of pixels in each dimension. Obviously the resolution changes as the image size changes because the number of pixels that make up the image are being spread over a greater or lesser area. Therefore the resolution changes accordingly.
Now, let's say you want to make a larger print — say one that was 14 inches wide. You would then end up with an image that was about 9.3 inches wide but more importantly one that would only have a resolution of 155 pixels / inch. This is not enough output resolution for a high quality print, as we'll see below."
- y aquí, en español:
http://fotopunto.com/confusion_sobre_la_resolucion_de_la_imagen_en_fotografia_digital
"Así, el concepto de "resolución" está siempre ligado al soporte o medio en el que se va a mostrar la imagen. Una imagen impresa con 300PPP en papel a 15x25 cm tendrá calidad fotográfica. Sin embargo, la misma imagen podría imprimirse tan grande como la fachada de un edificio si se hace con una resolución tan baja como 10 PPP, pero lógicamente no tendría calidad fotográfica (Y no sería necesaria ya que esos tamaños se miran desde muy lejos)."
(*) http://en.wikipedia.org/wiki/Spatial_frequency - "In image processing applications, spatial frequency is often expressed in units of cycles per millimeter and sometimes incorrectly in units of line pairs per millimeter (incorrect since a line pair may describe a square wave but not a sinusoidal wave)."
"There was nothing so very remarkable in that; nor did Alice think it so very much out of the way to hear the Rabbit say to itself, 'Oh dear! Oh dear! I shall be too late'."