Supplying a different DPI param per page

[Alec McLean]

If you have a multipage tif file is it possible that each page has a different DPI? If so, is there a way to extract the DPI values and then supply those as parameters for each page when you need to OCR images then produce an hOCR?

[Zdenko Podobny]

Just quick replay (I did not test it :-) ):

• tiff is"container of images" and AFAIK each image can have its own resolution (DPI is just information for correct printing/displaying of image)
• tesseract should read multi-page tiff  image-by-image and process it individually (including DPI information)

=> If each page/image in multi-page tiff have DPI info, tesseract should process it correctly

I am not sure how "--dpi" option would work in this case - IMO multi-page tiff scenario was not considered.

Zdenko

št 5. 3. 2020 o 18:41 Alec McLean <mclea...@gmail.com> napísal(a):

If you have a multipage tif file is it possible that each page has a different DPI? If so, is there a way to extract the DPI values and then supply those as parameters for each page when you need to OCR images then produce an hOCR?

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[Alec McLean]

Thanks for confirming that! Thats what the documentation hints at that but it was a little unclear to me, so I wanted to reach out.

On Monday, March 9, 2020 at 4:21:27 AM UTC-4, zdenop wrote:

Just quick replay (I did not test it :-) ):

• tiff is"container of images" and AFAIK each image can have its own resolution (DPI is just information for correct printing/displaying of image)
• tesseract should read multi-page tiff  image-by-image and process it individually (including DPI information)

=> If each page/image in multi-page tiff have DPI info, tesseract should process it correctly

I am not sure how "--dpi" option would work in this case - IMO multi-page tiff scenario was not considered.

Zdenko

št 5. 3. 2020 o 18:41 Alec McLean <mclea...@gmail.com> napísal(a):

If you have a multipage tif file is it possible that each page has a different DPI? If so, is there a way to extract the DPI values and then supply those as parameters for each page when you need to OCR images then produce an hOCR?

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