Image DPI restriction

[Vidur Malhotra]

Hi,

I was going through tesseract tutorials wherein it is mentioned that for Tesseract to do OCR, image should have alteast 300dpi. How is it possible? I tried capturing images from different phones (even iPhone 7plus), all of them are giving 72dpi.

[ShreeDevi Kumar]

For better recognition 300 dpi is recommended.

You can use a program like imagemagick to change dpi if needed.

On Mon, Jun 11, 2018 at 8:30 PM Vidur Malhotra <vidurmal...@gmail.com> wrote:

Hi,

I was going through tesseract tutorials wherein it is mentioned that for Tesseract to do OCR, image should have alteast 300dpi. How is it possible? I tried capturing images from different phones (even iPhone 7plus), all of them are giving 72dpi.

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[Armando Ota]

use scanner 

regards 

Armando

On Mon, 11 Jun 2018, 17:00 Vidur Malhotra, <vidurmal...@gmail.com> wrote:

Hi,

I was going through tesseract tutorials wherein it is mentioned that for Tesseract to do OCR, image should have alteast 300dpi. How is it possible? I tried capturing images from different phones (even iPhone 7plus), all of them are giving 72dpi.

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[zbgns]

Actual DPI is unknown as it depends on various factors (inter alia physical dimensions of taken object and distance you took the picture from). The easiest way to establish real DPI is to take photo of a ruler and count number of pixels on 1 inch distance. As an example, there is approximately 470DPI in case of picture taken from 18 cm with 12Mpixel camera (iphone 7).