inc ⇒ Pixel
inc
inc
dpi
= 1000 × 1000 pix

Pixel ⇒ inc
pix
pix
dpi
= 3 × 3 inc
Pixel & inc ⇒ dpi
inc
pix
= 300 dpi

DPI Calculator - Result

Total Pixels 1000 × 1000 Pixels      1 Mpx
Photo/Image/Picture Size 3 × 3 inc     
DPI / PPI 300 dpi
Color Depth 24 Bit    [ 224 ]    
Total Mb (binary) 2.86 MB    3000000 bytes
Pixel Size 84.6667 µm2       = (84.6667 · 10-3) mm2  

Photo/Image/Pictur Calculation Pixel DPI for printing and editing


Units
engl. measure 1 Inch = 25.4 mm
Dot per Inch 1 dpi = 1 Dot per Inch(25.4 mm)
pixels per Inch 1 ppi = 1 dpi = 1 Pixel per Inch(25.4 mm)
Digital B = Byte
1 bit = 0 | 1
1 B = 8 bit
1 kB = 1024 B
1 MB = 1024 kB
Example : pixels/Bytes calculate - image: 1000px · 2000px

\(Bytes = {Total pixels × color depth \over 8 Bit [1 Byte]}\)

\({(1000px · 2000px) × 24 \over 8 bit × 1M} = 6MB\)

Example: Photo/Image/Pictur 5x5 pixels (12.7 x 12.7 mm)
Formula calculation of length or width, pixels and dpi

\(length [mm] = {Pixel × 1 Inch [25.4mm] \over dpi}\)

\({5px × 25.4mm \over 10 dpi} = 12.7 mm\)

\(Pixel = {dpi × length [mm] \over 1 Inch [25.4mm]}\)

\({10dpi × 12.7mm \over 25.4mm} = 5px\)

\(dpi = {Pixel × 1 Inch [25.4mm] \over length [mm]}\)

\({5px × 25.4mm \over 12.7mm} = 10dpi\)

Image for print 300 dpi, for photo album
- Photo/Image/Pictur: 13 x 18 cm Quality of print 300 dpi
- Resolution in pixels?

Vertical 13cm [130mm]

\({300dpi × 130mm \over 25.4mm} = 1535 Pixel\)

Horizontally 18cm [180mm]

\({300dpi × 180mm \over 25.4mm} = 2126 Pixel\)

Total pixels [Mpx]

\({1535px × 2126px \over 1'000'000} = = 3.26 MegaPixel\)

Print Image 300 dpi, for photo album
- Image: 1024 x 768 pixels Quality of print: 300 dpi
- Which picture size for printing?

Vertical 768 Pixel

\({768px × 25.4mm \over 300 dpi} = 65 mm\)

Horizontally 1024 Pixel

\({1024px × 25.4mm \over 300 dpi} = 87 mm\)

slide scanning for a slideshow on the TV
- TV 40 inch Resolution : 1'920 x 1'080 pixels Photo-Slide : 24 x 36 mm
- Scan resolution?

Vertical 1'080 pixels 1080 Pixel

\({1080px × 25.4mm \over 24 mm} = 1143 dpi\)

Image Size Horizontally:

Horizontally 18cm [180mm]

\({1143 dpi × 36 mm \over 25.4 mm} = 1620 Pixel\)

Slide scanning for print a Poster
- Slide Size : 24 x 36 mm Poster Size : 900 x 600 mm Scanner Resolution: 4000 dpi DPI 1:1
- Scan resolution?
1. Pixels:

Horizontally 36 mm

\({4000 dpi × 36 mm \over 25.4 mm} = 5669 Pixel\)

2. Poster

Slide horizontally 36mm

\({5669 px × 25.4 mm \over 900 mm} = 160 dpi\)