Quote:
Originally Posted by nana77
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The video codec compression makes comparison and judging ereader screens almost worthless. Maths says you need photos at twice the finest detail, with twice the dynamic range and then a screen to view as good as that.
Quote:
Originally Posted by nana77
Can I misuse to ask if on a color device (where the 300DPI drops at 150DPI on color reads) is it possible to use them as a B/W but may choose other color's backgrounds (in place of using the frontlights)? If so does it drops the pixels ratio anyway?
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It's more complicated than that.
The 300 dpi mono screen has dots in a 2 x 2 pattern that don't fill the pixels, so that the screen isn't too dark. That means the brighter colours are all pastel and the darker colours lose colour. The underlying screen has white, black and approximately 14 grey levels.
R G
G B
pattern
So inherently you can't have good colour and any colour is limited to 150 dpi. Mono content is rendered at 300 dpi (unless an anti-rainbow setting, not on all ereaders is set, when it's 150 dpi). This means any strong pattern (especially either 45° or vertical or horizontal) alternating black and white at 300 dpi will have banding (a rainbow effect) and strongest artefacts can be yellow, cyan, magenta or green. However only certain fonts or images will have this effect.
The colour is printed dots that don't fill a pixel printed on top of the Carta 1300 screen, so they can't be turned off. Thus it's darker and poorer contrast as dots reflect more light than native Carta 1300 black.
Mostly the colour artefacts are not noticeable. May be worse with good reading glasses.
Why do LCD, OLED, QLED etc not have these artefacts?
1. Only eink runs the screen at underlying resolution. The LCD & QLED do use mono panels but they and OLED only run them at the colour resolution. LCD & QLED often has 1/3rd width native pixels to allow RGB. OLED may use the 2 x 2 array. Only the colour resolution is quoted on non-eink.
2. When screens were lower resolution RGB, often fonts had blue edges on one side and red on the other to pseudo triple resolution in one direction. Sometimes these artefacts were visible. Higher resolution and screens not using RGB stripes don't do the font enhancement.
3. The eink can't do decent anti-aliasing as it's 14 levels, black and white and the colour dots don't cover the pixels. The other current colour display technologies have black, white and 120 to 500 levels per pixel and the pixels are entirely coloured.
No LCD/OLED/QLED (or CRT in the past) maker claims resolution the way eink Corp does with Kaleido 3 eink (coloured dots printed on mono eink). The Gallery 3 isn't conventional eink and each pixel is C M Y W, not dots printed on a mono panel.
EDIT
It's in theory possible on Kaleido 3 eink to have a simple 300 dpi mono pure black & white (no greys) pattern that creates a 150 dpi image in a single colour (green, red, blue, yellow, magenta and cyan are simplest. It can only be prevented by rendering all monochrome content at 150 dpi, because the colour can't be turned off. It's translucent red, green, green or blue dots smaller than the pixels in a 2 x 2 pattern at pixel spacing.
The fast mode refresh for a B&W image or font with no greys can't be done with colour content. It will be slightly slower than full greyscale image. The eink doesn't have the kind of pixel refreshing of plasma, crt, LCD, oled etc. The Gallery 3 system is about x10 slower.