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[claude72]

The difference between vectors and pixels is here:
- the RIP rasterization of vectors can "cut" the screen dots to match exactly with the exact shape of the object,
- the RIP rasterization of pixels pictures leaves screen dots outside the shape and CANNOT "cut" the screen dots on the edge, leaving part of them outside the shape...
... and these extra outside and partially outside the shape screen dots are both altering the shape of the object (character or else) and create the haze.





Second consequence, as the pixels of a contone picture are not printable, when the picture is printed you don't see the pixels, but you only see the screen dots...
... and the sharpness of the picture (and the haze of a pixel text in Photoshop) doesn't depend of the resolution: of course there is a relationship between the resolution of the picture and the screen ruling, and there is a ratio to be used...

... but if you are within the acceptable limits of this ratio, the sharpness of your printed picture depends ONLY of the screen ruling: just have a look to the linked picture, showing together 4 different resolutions for the text, and you will notice that the resolution doesn't change anything: the very high resolution 2400 ppi picture is as crappy than the normal 225 ppi picture (225 ppi is the normal resolution for 150 lpi screen)...