CIS vs CCD Scanners.

[lordpain]

Hi,

I am currently new to scanners, planning to get one soon. Due to my reserach, I came across two sets of scanners: Color Contact Image Sensor (CIS) and Charge-Coupled Device (CCD).

May I know what are the differences?

From what I can see from the Canon models, 8800F and the LiDE700f, the LiDE has more optical resolution and is much cheaper. Comes in a smaller outfit too. Im sure there isn't such a thing as in cheaper and better in this world. Is there any setbacks towards the LiDE model?

If you have any insights, please do contribute to us newbies to scanners.

[sulhan]

Hi There...

CIS scanner sensors are typically in line for the whole width of the media scan - e.g width of the A4 scanner. The resolution really depends on the amount of sensor pixels throughout the whole width. A few sensors share a sensor light pipe lens surface that brings the "image in contact" from the media to the sensors. There will be a group of R|G|B led that turns on at high frequency one after another to scan each line scanned. These is then integrated to form the actual scanned line. This happens as the CIS scanner module moves across the scan window. Depth of field (DOF) of these CIS sensors are typically shallow but there might have some improvements there days. The shallow DOF will result in blurred scannings for objects that are physically away from the scanned surface - e.g the center portion of a thick book being scanned.

As for CCD scanners, they are normally constructed of a CCD sensor that is of a smaller dimension (width) of the scan line - typically consiting of R|G|B lines of sensor . A reduction optical path is created in between the actual CCD sensor and the actual scanned line surface. to allow compact system architecture.




As the CIS scanners are long scanners, they are physically constructed by joining about 5~7 segments of specific length.

Hope this helps...

[lordpain]

Wow,

Kudos to Sulhan once again for the comprehensive writeup. But really so which do I choose? A CIS or CCD? The Canon LiDE seems to have a better optical resolution; is cheaper and comes in a smaller outfit. Couldn't get any better than that right? From what you have explained, I don't really see any setbacks right?

[sulhan]

always ask if you need the resolution. If you want to take non flat on stuff for purpose of art content then the DVD one is the way to go. CIS And LIDE ones are slimmer usually. So find one that practically suits your needs.

[TME]

I've used scanners for quite some time now and I've actually used both types in a way that I guess most people would - scan stuff from books or documents...

I've used an Artec CIS scanner from way back in 1998 when CIS scanners first came out not long... and after that I deliberately bought a CCD scanner from Microtek (3700)... I have used a Canon LIDe 60 scanner at my workplace....

Actually for simple colour or black & white scans, there is little to choose between the image quality... the Artec I used some years back wasn't so good cos it was a relatively new technology then... my Microtek is has pretty good resolution and can capture very fine detail - even the image on the reverse side of the paper... but the Microtek being CCD based is very bulky... the Canon LIDe 60 (now already replaced by the 25, 45, 90, etc) performs just as well... and it's very very slim...

So I would really go for a Canon LIDe scanner now even though it's not the cheapest scanner in town...

The pros are:

1) Very slim, small compact, can be lugged around, takes up very little space

2) No need for an extra power block... it's powered via the USB cable... very very convenient actually... fewer wires...

3) Scanning 3D images is pretty ok, I don't have problems with that... in fact my issue is that when scanning pictures from magazines or text books, the resolution is an overkill and you see the image consisting of the print dots that the print process for mags and books undergo... hahaha... just like a portrait shot where the lens is so high resolution that you see every single pore and hair and pimple on the model's face... but can simply downres or tune down the original scanning res....

Hope this helps!

[grantyale]

CCD scanners have better depth of field. CIS ones are slimmer and has no optical distortion.
I used a Canon LiDE to scan old photo albums - some have page size larger than A4 and the paper is very thick, and the paper isn't always in contact with the glass. The parts lifted from the surface turned out quite blurry...

[TME]

Originally Posted by grantyale CCD scanners have better depth of field. CIS ones are slimmer and has no optical distortion. I used a Canon LiDE to scan old photo albums - some have page size larger than A4 and the paper is very thick, and the paper isn't always in contact with the glass. The parts lifted from the surface turned out quite blurry...

If you press the lid down, it should be fine...

[grantyale]

Originally Posted by TME If you press the lid down, it should be fine...

No it won't help. The album is made of very thick and hard card paper. Besides, the underside of the lid is foamy and gives in. CCD scanners are still better in handling things not in perfect contact with the glass.

[TME]

Originally Posted by grantyale No it won't help. The album is made of very thick and hard card paper. Besides, the underside of the lid is foamy and gives in. CCD scanners are still better in handling things not in perfect contact with the glass.

Huh?! That's absolutely not the right way to scan photos... you should be taking the photo out so that it lays flat on the scanner bed... any image captured by the CCD scanner will still be distorted... if the image is larger than the scanner bed, you should scan the photo in two parts and then merge the two parts in Photoshop or some equivalent photo-editing software...