CanoScan LiDE 300 skips several vertical pixels every 1728 pixels, visible on higher resolutions.

[johnl399371]

At 2400 dpi it skips 4 pixels every 1728 pixels.

At 1200 dpi it skips 2 pixels every 1728 pixels.

At 600 dpi it skips 1 pixel every 1728 pixels.

I've attached 200x200 segments of a 2400dpi scan at 1728 pixel intervals, you can see in the middle of each section several pixels are skipped. This issue is particularly evident on high detail areas and diagonal lines.

example.png

High detail example:

example2.png

How can I prevent this from happening?

[shadowsports]

Greetings,

This is is a known hardware limitation.  I took this directly from AI. These are not my own words.  

Why this happens. 

• Sensor Grids: Scanners read documents line by line using a fixed-width sensor array. The number 1,728 corresponds to the standard number of pixels in a standard-width digital facsimile line.

• DPI Scaling Ratios: At 600 DPI it drops 1 pixel, at 1200 DPI it drops 2 pixels, and at 2400 DPI it scales up to dropping 4 pixels at those exact 1,728-interval thresholds.

How to resolve

• Use Non-Standard Resolutions: Avoid neat multiples of 300 or 600. Forcing an arbitrary resolution like 2399 DPI or 1199 DPI in advanced scanning software breaks the mathematical loop, altering how the internal firmware recalculates grid stitch boundaries.
• Scan in Landscape Orientation: Turn your document 90 degrees on the glass. The pixel-skipping boundary error occurs along the horizontal sensor array (the X-axis step). Scanning sideways forces the critical fine details to line up along the continuous physical motor movement axis (Y-axis) instead.
• Switch Software Interfaces: If using basic Windows Fax and Scan, switch to the official Canon ScanGear Utility and turn off all "Auto Image Correction" features, which often compound interpolation errors.

[johnl399371]

hi, the AI doesn't understand the issue. (LiDE 300 can't even change DPI arbitrarily, it's preset)

I'd like to know if the hardware is incapable of not skipping parts of the page or if there's potential for a driver patch. I've had other canon scanners without this issue so it surprises that the currently sold and supported model does.

[shadowsports]

Greetings,

I think it understands it just fine. 😉

This was not taken from AI and is my own words.

This behavior is a hardware restriction imposed by the multiple photo diodes in the image bar.  The lide 300 and 400 do not use a single image sensor. They use multiple smaller sensors (CIS) across the entire scan bar.  The device uses firmware to stitch image data together to the supported 8.5 in. horizontal width of the x-axis.  Because the machine does not use a single image sensor, pixels can be skipped depending on the resolution you select every 1,728 pixels.  This is a standard mathematical calculation.  This may not be true of other brand scanners (which I cannot speak to) but it's how the Canon (300/400) scanners work.  

The lide 300 is an entry-level scanner. So depending on the image resolution that you select, you can miss one pixel or more (depending on the resolution you select) at the end or beginning of the next line. 

27 sensors, each capable of capturing 64 pixels equals 1728 pixels.