What is the best resolution for my photos, wall art and posters?

What is the best resolution for my photos, wall art and posters? 
(See below for Aspect Ratios of each print and poster.)

Higher resolution photos are clearer and contain more detail.

Digital image resolution is expressed as pixels (or dots) across by pixels down, such as 640 x 480, meaning 640 pixels across by 480 pixels down. The best printable resolution is 300 dots per inch. 

Extremely low resolution will look "blocky" or pixelated. Imagine only 4 dots per inch: you would see four colored squares instead of a picture. When there are many pixels, your mind blends the tiny blocks together to form an image.

The digital camera is the most important factor in determining quality of digital images. The greater the number of pixels (up to 300 per inch), the higher the quality of the digital image. Some low-cost cameras give a set number of pixels and shoot only one resolution. Higher-priced cameras offer a pixel range, which enables you to select the best resolution for the size image you want.

Not all photos require high pixels per inch. For instance, you are likely to stand back from a poster, and your eye will blend the pixels together, so 90 pixels per inch is the minimum recommended resolution for posters. The subject matter can also be important: for instance, if you are printing a picture of a crowd of faces or a group shot, and you want to recognize faces in the crowd, you will need a higher pixel count to ensure that each tiny face has a enough visual information.

Use the following chart as a guide for determining the best resolution for various print sizes.  Note that the 4xD (Digital) size is the same ratio as most digital cameras -- 1.333 (1200 x 1600 dots) -- so no cropping is required when printing these photos. The 18x24 and 30x40 also have the same 1.33 ratio and require no cropping for most digital cameras.
Add an eighth of an inch to each side for a perfect print

When creating a print product like a 4x8 card or poster, add 1/8 of an inch to each side.  For 300 dots per inch, that's 37.5 pixels or 75 pixels for both sides. A perfect 4x8 card would be ((4x300)+75) X ((8x300)+75) or 1275 by 2475. The 37.5 pixel border is not printed, so no important photo elements (faces, type, etc.) should be in that space. Note that the 1/8 inch pixel border decreases as resolution decreases: at 200 dpi, 1/8 inch is 200/8 or 25 pixels. This also changes the aspect ratio.

150 res
180 res
200 res
300 res
Ratio (L/S)
Wallets (2"x3")300 x 450 360 x 540 640 x 480 600 x 900 
4 x D (4 x 5.33)600 x 800720 x 960800 x 10661200 x 1600
4 x 6600 x 900720 x 1000800 x 12001200 x 1800
4 x 8 Card638 x 1238765 x 1485
850 x 1650
1275 x 2475
5 x 7750 x 1050900 x 12601000 x 14001500 x 2100
8 x 101200 x 15001200 x 15001600 x 20002400 x 3000

90 res
150 res
180 res

300 res*

Ratio (L/S)
11 x 14990 x 12601650 x 21001980 x 25203300 x 4200
12 x 181080 x 16201800 x 27002160 x 32403600 x 54001.50
16 x 201440 x 18002400 x 30002880 x 36004800 x 6000* 1.25
16 x 241440 x 21602400 x 36002880 x 43204000 x 6000*1.50
18 x 241620 x 21602700 x 3600 3240 x 43204500 x 6000*1.33
20 x 201800 x 18003000 x 30003600 x 36006000 x 6000*1.00
20 x 241800 x 21603000 x 36003600 x 43205000 x 6000*1.20
20 x 301800 x 2700 3000 x 45003200 x 4800*4000 x 6000*1.50
24 x 362160 x 32403200 x 4800* 3200 x 4800* 4000 x 6000*1.50

30 x 402700 x 36003600 x 4800* 3600 x 4800*4500 x 6000* 1.33
* The longest side of any uploaded image is a maximum of 6000 dots. When the longest side is 6000, the other side is calculated to have the same number of pixels per inch.

What is the best resolution for a large poster or framed print?
The largest image that dotphoto uploads is 36 megapixels or 6000 x 6000 dots, so, if possible, you want the longest side to be 6000 dots and the shorter side to be proportional. For instance, if you want a print that is 42" x 30", the best possible image would be 6000 x 4286. The image must also be 30MB or less; if the original is more than 30MB, try saving as a JPG or adjusting the JPG compressions.

How can I see the size of my images in dotphoto?

  1. Tap the album you want to inspect.
  2. Tap the Organize menu on the left.
  3. Tap the Edit Titles menu. You will see the Width and the Height in pixels of each photo in the album.

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