MobileRead Forums - View Single Post - do-it yourself repro v-cradle for paper books

ereszet · 10-21-2007, 03:56 PM

Long overdue Finereader 9 has been released. I will test it and report the results in this thread as soon asr I buy it. In the meantime I quote below some hints regarding photo scanning from:
http://abbyy.com/DLCenter/downloadce...de_English.pdf

1. Make sure that the page fits entirely within the frame.
2. Make sure that lighting is evenly distributed across the page and that there are no dark areas or shadows.
3. Straighten out the page if required and position the camera parallel to the plane of the document so that the lens looks to the center of the text being photographed.

Minimum Requirements
. 2–megapixel sensor
. Variable focus lens (fixed–focus cameras, common in cell phones and hand–held devices, will usually produce images unsuitable for OCR)
Recommended Requirements
. 5–megapixel sensor
. Flash disable feature
. Manual aperture control or aperture priority mode
. Manual focusing
. An anti–shake system, otherwise the use of a tripod is recommended
. Optical zoom

Shooting Modes

Lighting
Make sure there is enough light (preferably daylight). In artificial lighting, use two light sources positioned to avoid shadows. (ereszet remark: this is not necessary with the v-cradle design; one bright overhead light source and a light diffusor is recommended).

Positioning the Camera
If possible, use a tripod. Position the lens parallel to the plane of the document and point it toward the center of the text.
At full optical zoom, the distance between the camera and the document must be sufficient to fit the entire document into the frame. Usually this distance will be 50–60 cm. (ereszet remark: tripod with a ball head is not preccise enough to set the camera angle and distance to match different size paper documents every time they change; repro copy stand with micrometer plates will save you a lot of positioning effort; with a tripod, once you position the camera, do not touch it anymore, do all the distance and angle positioning with the v-cradle instead).

Flash
Whenever possible, turn off the flash to avoid glare and sharp shadows on the page. In poor lighting conditions, try using the flash from a distance of about 50 cm, or, preferably, use additional lighting.
Important! Using the flash when photographing documents printed on glossy paper causes the worst glare. (ereszet remark: see my post on redirecting the flash to the ceiling; glare does not interfere with the shots taken with the v-cradle setup).

White Balance
If your camera allows, use a white sheet of paper to set white balance. Otherwise, select the white balance mode which best suits the current lighting conditions. (ereszet remark: white sheet of paper may not work in bright sun; see an example in one of my previous posts; try Kodak grey card instead).

Auto focus may not work properly in poor lighting or when photographing at a close distance. In poor lighting conditions, try using an additional light source. When photographing a document up close, try using the Macro (or Close–Up) mode. Otherwise, if possible, focus the camera manually (ereszet remark: set the zoom and preview the focus with PSRemote remote capture program; if a page is almost blank with a few lines of text use another page of text to set the focus and fix the focus.)
If only a part of the picture is blurred, try reducing the aperture value. Increase the distance between the document and the camera and use maximum zoom. Focus on a point anywhere in between the center and a border of the image (ereszet remark: as long as that point is not a blank part of the page).

10-21-2007, 03:56 PM	#93
ereszet Zealot Posts: 118 Karma: 306 Join Date: Sep 2007 Device: Sony PRS-500 Archos 704 wifi	Some hints regarding photo scanning from Finereader 9 Long overdue Finereader 9 has been released. I will test it and report the results in this thread as soon asr I buy it. In the meantime I quote below some hints regarding photo scanning from: http://abbyy.com/DLCenter/downloadce...de_English.pdf 1. Make sure that the page fits entirely within the frame. 2. Make sure that lighting is evenly distributed across the page and that there are no dark areas or shadows. 3. Straighten out the page if required and position the camera parallel to the plane of the document so that the lens looks to the center of the text being photographed. Minimum Requirements . 2–megapixel sensor . Variable focus lens (fixed–focus cameras, common in cell phones and hand–held devices, will usually produce images unsuitable for OCR) Recommended Requirements . 5–megapixel sensor . Flash disable feature . Manual aperture control or aperture priority mode . Manual focusing . An anti–shake system, otherwise the use of a tripod is recommended . Optical zoom Shooting Modes Lighting Make sure there is enough light (preferably daylight). In artificial lighting, use two light sources positioned to avoid shadows. (ereszet remark: this is not necessary with the v-cradle design; one bright overhead light source and a light diffusor is recommended). Positioning the Camera If possible, use a tripod. Position the lens parallel to the plane of the document and point it toward the center of the text. At full optical zoom, the distance between the camera and the document must be sufficient to fit the entire document into the frame. Usually this distance will be 50–60 cm. (ereszet remark: tripod with a ball head is not preccise enough to set the camera angle and distance to match different size paper documents every time they change; repro copy stand with micrometer plates will save you a lot of positioning effort; with a tripod, once you position the camera, do not touch it anymore, do all the distance and angle positioning with the v-cradle instead). Flash Whenever possible, turn off the flash to avoid glare and sharp shadows on the page. In poor lighting conditions, try using the flash from a distance of about 50 cm, or, preferably, use additional lighting. Important! Using the flash when photographing documents printed on glossy paper causes the worst glare. (ereszet remark: see my post on redirecting the flash to the ceiling; glare does not interfere with the shots taken with the v-cradle setup). White Balance If your camera allows, use a white sheet of paper to set white balance. Otherwise, select the white balance mode which best suits the current lighting conditions. (ereszet remark: white sheet of paper may not work in bright sun; see an example in one of my previous posts; try Kodak grey card instead). Auto focus may not work properly in poor lighting or when photographing at a close distance. In poor lighting conditions, try using an additional light source. When photographing a document up close, try using the Macro (or Close–Up) mode. Otherwise, if possible, focus the camera manually (ereszet remark: set the zoom and preview the focus with PSRemote remote capture program; if a page is almost blank with a few lines of text use another page of text to set the focus and fix the focus.) If only a part of the picture is blurred, try reducing the aperture value. Increase the distance between the document and the camera and use maximum zoom. Focus on a point anywhere in between the center and a border of the image (ereszet remark: as long as that point is not a blank part of the page).