Barnes and Noble Nook Color has a pixel density of:
169.55

A.K.A. Nook Color Tablet
Released: 2010

Resolution: 1024×600 7″ display

Totaling 0.61mp (megapixels) and having a PPI of 169.55

Category: E-Reader
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Barnes & Noble Nook Color

Wikipedia on the Nook Color
Manufacturer	Barnes & Noble
Release date	16 November 2010 (2010-11-16) (Wi-Fi only)
Introductory price	US$249; US$139 (current)
Operating system	Android 2.2 Froyo custom (software update – ver 1.4.3 [06/20/2012])
CPU	800 MHz ARM Cortex-A8-based TI OMAP3621[1]
Memory	512 MB
Storage	8 GB internal 32 GB max via microSD
Display	7-inch 1024 x 600 px WSVGA IPS LCD at 170 ppi
Graphics	PowerVR SGX 530
Input	Capacitive multitouch screen with side volume, Nook Home, and power button
Connectivity	Wi-Fi 802.11 b/g/n, USB, Bluetooth(Disabled on stock firmware)
Power	Installed battery 3.7 v  4000 mAh (8 hours with Wi-Fi off)
Dimensions	8.1 in (210 mm) H 5.0 in (130 mm) W 0.48 in (12 mm) D
Mass	15.8 oz (450 g)
Successor	Nook Tablet
Website	Official website

This righthand infobox courtesy of Wikipedia.