4 white pixels, please help. - DPChallenge Forums

Canon EF-S 18-55mm f/3.5-5.6 IS

02/22/2005 12:46:41 PM · #1

I need help. My Olympus C-740 seems to have developed a problem. In every picture that the lighting is either dim or dark, I get 4 white pixels almost dead center of the image, every time. The first thought would be the lens, but I don't see any scratches, or blemishes on my lens. If I zoom in on the image so far as to see individual pixels, its 4 that are completely white. I'm guessing that the camera may have a problem not receiving data, where those 4 pixels lie. Has anyone had this problem? Speaking of zoom, if it was a problem with the lens, and I zoomed in on a subject, I would guess that the blemish would increase, or look slightly different. Nope, no matter how the picture was shot, I get these 4 white pixels, in the same exact spot.

As far as challenges are concerned, when I resize the picture to submit, the pixel block will shrink to where you have to strain to see it and barely noticable, and if I'm editing it for my own prints, I can just clone right over it, but I'm upset that this is even happening. Does anyone know what might be the problem, or how to solve this within the camera itself? And don't get smart either, like, "Dude buy a D-70", or something. I need help.

Mike

justinbrook

Canon EOS-60D

02/22/2005 12:49:48 PM · #2

I heard of a similar problem before. If I remember correctly it was the CCD that was damaged. Not sure if you can clean it or if it needs replacing.
Try the Olympus helpline to see if they have heard of it before.
Goodluck

Bear_Music

Samsung Galaxy S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

02/22/2005 12:53:16 PM · #3

Almost certainly a block of dead sensors. Is the camera still under warranty?

Robt.

Olympus 40-150mm f/2.8 PRO M.Zuiko

02/22/2005 12:56:16 PM · #4

The warranty is expired. I'm going to try and contact Olympus. I figured I'd ask here first, and it looks like I'm not alone with this issue. At the risk of sounding like a dumb newbie, what is the CCD?

Thanks for your input.

Brad

Olympus OM-D E-M1

02/22/2005 12:58:27 PM · #5

Does your Olympus have pixel mapping capabilities?
My E-10 has a program built in that can be selected, and "looks" for such problems (stuck/dead pixels in the CCD), takes a little of each adjoining pixel and writes over the dead sections in it's software. It's a manually selectable option that must be activated in the setup screen.
Just an idea.

Brad

Olympus OM-D E-M1

Olympus 40-150mm f/2.8 PRO M.Zuiko

02/22/2005 12:59:36 PM · #6

Originally posted by phreakon:

At the risk of sounding like a dumb newbie, what is the CCD?

Not a dumb question. It's the imaging sensor itself.

Bear_Music

Samsung Galaxy S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

02/22/2005 01:00:37 PM · #7

The CCD is the digital equivalent of the film. It's a Charge Coupled Device which is covered with tiny sensors that read the light falling on them and transmit the information to a chip that digitizes and image ans sends it to the memory card for you. The larger the Mp (megapixels) designation of your CCD, the finer the detail it can resolve. A 4Mp CCD has half as many sensors as an 8 Mp CCD, and each sensor is correspondingly larger. Think of them as the "grain" equivalent.

Robt.

ScottK

Canon EOS-350D Rebel XT

Canon EF 28-135mm f/3.5-5.6 IS USM

02/22/2005 01:05:44 PM · #8

The CCD is the sensor which actually collects the light and records the image. Its made up of all those millions of pixels, or cells. The cells can either "die", which results in dead pixels, which (as I understand it) show up as black. Or, they can become overly sensitive, resulting in "hot pixels", which usually show up white or possibly one of the primar colors (red, blue or green, depending on which pixel is stuck - see the info here - but skip the first section on Faveon sensors - not relevent).

I'm pretty sure there are some apps out there to "map" out dead or hot pixels, though I haven't used any. I think they just sort of guess at a probably value, based on the surrounding pixels.

For DPC advanced rules challenges you can just clone them out. For basic rules, you definitely can't clone them out, but I don't know if there are other acceptable methods that would be legal.

Canon EF 28-135mm f/3.5-5.6 IS USM

02/22/2005 01:09:44 PM · #9

I don't think it has pixel mapping. I'll take a look at the manual and see, but I'm pretty familiar with the camera functions, and I don't recall seeing anything like that. I could be wrong.

ScottK

Canon EOS-350D Rebel XT

02/22/2005 01:17:07 PM · #10

edit: Ooops, you were responding to Brad. Never mind.

Message edited by author 2005-02-22 13:18:26.

Pentax SMC DA 18-55mm f3.5-5.6 AL WR

02/22/2005 01:18:04 PM · #11

As far as the challenges are concerned, I don't need to worry because I resize the pic to reduce file size, and it doesn't completely go away, but you won't notice it. I have really to strain to see it.

Okay, I'm on the phone with Olympus, and I have to send the camera to get repaired, but it does have pixel mapping. I was mistaken.

drz01

Pentax K50

02/22/2005 01:41:14 PM · #12

Olympus have pixel mapping so it can map out bad pixels

kirbic

Canon EOS R5

Canon RF 24-70mm f/2.8 L IS

02/22/2005 02:51:41 PM · #13

Originally posted by phreakon:

I don't think it has pixel mapping. I'll take a look at the manual and see, but I'm pretty familiar with the camera functions, and I don't recall seeing anything like that. I could be wrong.

You may not see a reference to this in the manual, particularly if it is not something the end user can perform. Many cameras do have the capability though, because the "perfect" CCD has yet to be made. They all, sooner or later, need to have some pixels mapped out. Virtually all of them have at least a few mapped out right from the factory.
Call Oly, their tech support folks should be able to tell you how and if this can be done.

Edit:
According to one review site, the c-740 has "automatic pixel mapping". I don't know exactly what the "automatic" implies, I'd still call Oly and see what they say.

Message edited by author 2005-02-22 14:53:46.