Confusion over megapixels vs. megabytes

Hello John,

The number 14.2 refers to the number of PIXELS which can make up the picture your camera can take at its' HIGHEST QUALITY image setting i.e. 14.2 megapixels - which means 14.2 million pixels. Each pixel is a tiny part of the picture.

The 'size' of the picture e.g. 3.2meg or 1.8meg refers to how much space the picture takes up on any memory card i.e 1.8 or 3.2 megabytes (megabytes and megapixels are NOT the same thing).

By way of explanation the more pixels a camera uses to make and take a picture, the better the picture quality should be, but the more pixels there are in a picture the larger amount of space it will take up on the memory card that the camera uses.

I don't know what size or type of card is used in your camera, but if your camera is used at its highest quality image setting of 14.2 megapixels, then I would expect each picture to take up MORE space than 1.8 or 3.2 megabytes. Therefore setting that your camera is using to create a picture of 1.8 or 3.2 MEGABYTES in size is probably NOT the highest quality setting.

Your camera may have settings that allow you to adjust the picture quality in several steps from the best quality (most pixels - and therefore largest size IN MEGABYTES) - down to the 'lowest quality image' which will take up the least amount of space on the card IN MEGABYTES that the camera uses - which will have the effect of allowing you to take more pictures using the said card if the settings of the camera are left at the 'lowest quality image'

As an example I still use a Canon Powershot G5 (which has 'only' 4 megapixels) with its highest image quality setting (called 'superfine') and my pictures are stored on a couple of 128 Megabyte cards. The size of these pictures (at about 2 or 3 megabytes) is about the same as that on your camera, which uses three times as many pixels. These cards are quite small compared to what you can get nowadays, but I can still get loads of good quality pictures on them. If I used a 1 or 2 Gigabyte card I could get hundreds of best quality pics on it.

In the case of your camera with 14.2megapixels, the smallest card you should want to use if the camera is at its' highest quality image setting would probably be about 512 Megabytes or 1 Gigabyte (1 Gigabyte is approximately 1000 Megabytes) to get a decent number of best quality pics before the card is full up.

Also your camera having 14.2 megapixels also means that it should be able to use a much bigger card (for bigger read 'more space' not actually physically bigger) than than a camera with say about 4 or 6 megapixels.

The more spacious the card the more pictures you can put on it at the highest setting, but the more the card will cost.

I hope this info helps, and is not too confusing

Rob

As pixel count goes up, file size becomes a major concern. An uncompressed TIF file of a 24-bit RGB image at 10 megapixels is about 30 megabytes. At that rate, a 1gb flash card could hold no more than 30 photos. When saved as an LZW compressed TIF image instead, the same photo could be as small as 280kb if it was a photo of a polar bear in a snow storm (all one color.) Save the exact "Polar Bear in a Snow Storm" image as a compressed JPG file at 50% quality and the size goes down to 59kb.

Actual 10 megapixel photos of average complexity would have the following sizes: TIF=30mb; compressed TIF=12mb; high quality JPG=1.4mb; medium quality JPG=.8mb (800kb); and low quality JPG=400kb. The same 1gb card that could store only 30 TIF images could hold over 700 high-quality JPG files, or over 1,200 medium quality JPG files.

Your camera allows you to specify the amount of compression to use. The manufacturer has established a default to make the camera more user friendly. The naked eye often cannot see the difference between an uncompressed TIF and a high-quality JPG, so the factory setting normally defaults to HQ-JPG. Other manufacturers opt to use medium quality JPG to store more images in the same space.

You can set your own default on your camera. Just check the user manual under the heading of "image quality" for instructions.

You're getting mixed up between how the picture is put together, and how much memory is needed to store it.

Pictures are put together in little dots, or pixels (you can see them if you look closely at your monitor, or at the TV screen). Your 14.2 megapixel Nikon uses 14.2 million of these dots to make up a photo.

When you take a photo, what the camera sees is converted into these dots, and the "colour" of each dot is stored in memory. When you want to view the picture, your computer (or whatever you use) goes to the memory and finds out what each dot should look like for that photo, and puts it up on the screen, thus reconstructing the photo.

You can imagine that it would take a lot of computer memory to remember what 14.6 million dots look like. In your Nikon case, it takes 1.8 megabytes of memory. That's where that figure comes from.

By contrast, your Kodak camera has 12 million dots per picture, and this takes 3.2 megabytes of memory to store. Why is it more memory for fewer dots? One reason is that some computer chips are more efficient than others, but the other may have to do with your "resolution" settings.

"RESOLUTION": You can change the memory needed for each photo by altering what's called the "resolution" setting on your camera. That is, if you like, how many dots you want your camera to remember when you take a photo. It doesn't have to remember all the available dots (you might tell it to just remember half of them, for example), but if you choose to do this, you will lose a bit of sharpness. This is called "lowering the resolution", which you might do to save on memory (or megabytes - your camera, like your computer, has a limit).

You might have heard of a photo looking "pixelated'. This is when very low resolution has been used (relatively few pixels), and you can start to see the individual pixels or dots when you look at the photo.

Fewer dots remembered means less memory (megabytes)used, but loss of sharpness (this is low resolution). More dots remembered means a sharper picture, but more memory used (this is high resolution).

It's always best to use high resolution for your photos, but you have to remember that you can't take so many photos like that - you will run out of memory sooner. If you think you might run out of memory, then you need to lower the resolution and put up with photos that are not quite as sharp. Much of the time this won't matter, as they will still usually be very good.

Remember also that you will need to store your photos somewhere, so the memory capacity of your storage must also be taken into account.

Final note: the resolution setting on your camera might not mention the word "resolution". One I'm looking at now says "Quality", and tells me how many "frames", or photos, I can get for each quality setting. Higher quality = fewer frames. Another camera I have seen gives the resolution in: pixels across times pixels down. So it might say 1536 x 1180, which would be 1.8 megapixels (1536 x 1180 = 1 812 480). Your camera manual will help if you can't figure this out.

I think the problem here is a misunderstanding of the term "megs" so heres how the lowdown

The Megs you are referring to when you say the picture is always less than 2 megs is a file size. When you take the picture it is stored as bytes, a lot of bytes, so many infact we have a special unit for it, Megabytes. so the Pictures you are taking are around 2 Megabytes in size, thats about 2,000,000 bytes. this is a fairly large file.

The Megapixels you are referring to is the physical size of the picture, or more precisely the size of the image sensor (the digital "eye") in your camera. This means simply that the picture will be composed of 14,200,000 pixels. A pixel is simply one piece of the picture. This alternatively translates to a resolution. The higher the Megapixels (presumably) the less pixelation or "boxiness" you will get in the final imiage.

In short, Megs is just a prefix that means "million" so a megabyte is a million bytes (about) a megapixel is a million pixels and a megaton is a million tons.

Your next question comes as you compare the file sizes of two differnt cameras, this seems to be the most answered question here so i will go over it quickly. When you take the picture of that tree, you now have an image that is 14.2 million pixels, and a file that is very large. This presents a problem as the memory card in your camera is probably only a few GBs (Gigabytes or 1,000,000,000 Bytes) this means that you could only keep a few of your pictures before you ran out of memory and had to use a new card. To fix this, your camera uses technology to compress or squish your picture into a smaller file (think of a pillow being squished into a small bag) this means the picture that used to be 10 MB is now 2MB, and you can keep hundrads or even Thousands of pictures on your Memory Card.

Now for the useful part, unless you are tacking pictures for posters or very large prints, you can probably get by with a slightly reduced resolution and a higher compression (smaller file size) which means you can take more pictures before you need to transfer them to your computer. For normal picture taking I would recommend that you use a medium sized picture with a normal compression.

I hope this is helpful and clears up some of your confusion (after reading the responses you dont seem to be the only one confused by this) Good Luck and be sure to Share those pictures!

A pixel is ONE piece of a picture. PIX ELement.
Take a very close look at any video monitor. You will see either three color dots in a triangle or three color lines next to one another. These dots or lines are repeated over the whole screen.
If the resolution of the monitot/tv is full HD it is 1920 by 1080 which means one picture contains 2,073,600 pixels. (1920 times 1080).
In camera terms 14.2 megapixels is the # of sensors vertically times the # horizontally behind the lens.
When this image is recorded in a file, the size of the file is determined by the TYPE of file that is saved. It could be RAW (no compression), it could be TIFF (little to no compression but with less pic info than RAW, or it could be JPEG (little to a lot of compression).
The other factor is that each color of each pixel is saved as a separate byte and the luminance info is saved as another byte - the color may be saved as 2 bytes.
A RAW file with a 14.2 MP sensor will be very large.
A JPEG file will be more the size you are getting. The exact size depends on the QUALITY you have selected and the resolution.
Try setting your camera for the highest quality, the highest resolution, and RAW if available, or TIFF. If neither of those formats are an option, then it will compress it to JPEG with highest quality or most bits per pixel.

You did'nt tell under what format the images where saved. Is it JPG, PNG, BMP, RAW,...?
Anyway, there is no solid relation between resolution, the number of pixels, and file volume, the megs.

A pixel is a point of the image. Each pixels is composed of a red, a green and a blue components that can have a variable dimention, but usualy is set to 8 bits or 1 byte per colour for 16.4 millions colours or "true colour".

Then, you have the dimention of the file that contains that information, and here the things get interesting. You can save the image as a RAW file (very big) or BMP (also very big), or into a compressed format, such as JPG or PNG. The compressed formats have various compression capabilities, and may or may not be lossy.
A PNG or RAW may use some arbitrary colour depth, up to 16 bits (2 bytes) per channels, or billions of colours.

At 3 bytes per pixels (true colours), an uncompressed 12 megapixels will be 36 megs, and a 14.2 megapixels will be 42.6 megs. So, all your images ARE compressed.

Your Kodak camera got a compression ratio of about 90%.
Your Nokon camera acheive a higher compression ratio at about 95 to 96%.

If you Nikon saves using JPG, you should change the setting to some other format, as JPG discard some informations while compressing, thus the term "lossy" associated with that format.
If you want compression, use the PNG format. Slightly larger but not lossy.

If you want to do ANY image processing you must use a non-lossy format.

In a simple way:
Megapixel: is related to the photo size (inch size)
Megabyte: means how bulky will result your photo.

Megabyte depends on the camera manufacturer for the compression level applied to the photo, for that reason two images of equal megapixel but different brand cameras have different size in megabyte (because are using different programs for compressing the images)

mega pixel's are a measurement of scale (how many little squares make up the image) not file size. megabytes is the measurement of it's size.

2 things can cause a smaller size at 1.8Mb I would assume you're camera is set to normal quality at 4-6 Mega pixels. If you go into your camera Menu you can up the quality to Fine and the resolution to a larger Mega pixel setting.

Megapixels and megabytes aren't really related at all.

A pixel is a very small block of colour. A digital photo is made of thousands or millions of individual pixels. The more pixels an image contains, the greater its detail (quality). One million pixels equals one megapixel, so a 14.2 megapixel digital camera can take photographs that contain more than 14.2 million pixels.

A megabyte is not representative of the quality of your images, it measures the file size. The more megapixels contained in a photograph, the more megabytes (MB) it will consume. (The better the quality of the image, the larger the file size.) The file format also has a lot to do with the file size (megabytes) of your image. E.g. a 14.2 megapixel photo saved as a jpg might take up about 3 megabytes but the exact same photo saved as an uncompressed tif file might be about 15 megabytes.

Hope this helps

Think of a pixel as one little dot that makes up an image. A 12-megapixel digital camera can create a picture that's 4,000 pixels wide by 3,000 pixels high. Now, megabytes are how computers store information; they've got nothing to do with what's being stored. Typically, yes, larger images take up mroe space, but if you compress the image a whole bunch, it can take far less room on your computer than a smaller picture that hasn't really been compressed.

Try to imagine an 8-inchX10-inch physical photograph and a wallet-size print. You can take the former and fold it up a bunch, and cram it into a really small space. It'll look a lot worse, now, but it's still a "large image" that takes up a small amount of room.

The 14.2 Mega pixels refers to the photo diode array that captures the picture. The mega byte size of the picture is the photo quality. You can't change the former but you can change the setting of the latter by adjusting the camera settings. As has been said many times, "When all else fails, read the instructions." You'll need to read how to adjust the picture quality. Undoubtedly you are saving pictures in a low quality JPEG format. You can probably increase that to 4.7 megs per picture with the camera settings. Or, you can change the format to TIFF which will provide a 9.8 meg picture.

Your camera with 14.2 mega pixel photo diode array is very good-----a high end amateur camera. This will allow you to blow pictures up to 12 x 18 with great quality and even larger for a little sacrifice in quality.

Stardards of these prodcer are different from others,then cause showing different properties. The key is to consistency of criterion in all digital camera's prodcers

The short answer is "Apples and Oranges." That is, megapixels and megabytes are completely unrelated. But don't let it bother you, because the longer answer starts with telling you that you're SUPPOSED TO BE CONFUSED, so the camera manufacturers can sell more expensive cameras than most of us need.

Megapixels are a measure of the number of light sensing "dots' on your camera sensor (the "electronic film"), much like the pixels on your computer screen. The difference being these pixels collect light, not display it. The more dots, the more information you can record, and the better (ostensibly) resolution you get. Every picture you take utilizes all 14.1 megapixels. Megabytes is the amount of disk space needed to store your picture, just like an email or a report for work. Depending on the format you choose (RAW, jpeg, etc.) the file size will vary. The settings you use to process the saved image will also affect the size.

Don't worry too much about the technical reasons, just realize that megapixels and megabytes are as different as your computer screen and your hard drive. It's not a 1:1 ratio, and there's no direct relation between the two.

To better understand meagapixels (and the "dirty truth" about them) I urge you to read "The Megapixel Myth" by Ken Rockwell (http://www.kenrockwell.com/tech/mpmyth.htm), an independent photo enthusiast (engineer by trade) who is very generous with his advice and expertise. His site will help you with megapixels, megabytes, why more isn't necessarily better, and a lot more.

First- megapixels is the total sensor points for each color. So multiply by 3(red, green, blue) and an image is ~42 megabytes. This would only be the actual file size if an uncompressed image is saved.A scanner set to save a TIF file will do exactly that. JPEG files that your camera saves will vary in size due to the subject and your choices. You can set a JPEG for fine detail or less. You can set the camera to save a file with less pixels, i.e. you choose 10MP or 8MP. Finally, a RAW file does smart compression,so it can be smaller with no loss of quality.

Megpixels refers to the number of pixels in the image...it's akin to screen resolution. The higher the megapixel rating...in theory...the better quality picture you get. There are also other factors involved that effect that as well. Megabytes is the size of the file. Just becaue you have a camera that is 14 megapixels doesn't mean the resulting image will be 14 megabytes. The two are totally unrelated. Now as far as why one takes a pic that is smaller in size than the other depends on setting like resolution, compression, colors, etc... One of your cameras might be using an older compression scheme that isn't as efficient so it produces a larger image.

Megapixels are sizes based on the number of dots that make up a picture. The seconds part of the equation is the how many colors aer used to make the picture.

The file size of your picture will vary depending on what file format is used to store your file onto your camera memory.

I did a quick internet search and found this URL that might help explain things in more detail.

http://web.forret.com/tools/megapixel.asp

You might also find this URL useful because of the calculator and the little image on the right that display the aspect ratio of the image as well.

You will notice that JPG , BMP...etc all vary in size for the same image size. Many cameras save files in JPG format allowing for more photos to be stored onto the memory because this file format compresses the image.

A pixel or megapixels is the tiny dot that comprises a picture. You can see it only if you magnify the picture. A byte or megabyte is the measure of disk space that a file will consume. A poster picture will have more megapixels than a tiny picture. But a simple picture, let us say a black straight line on a white background will require less memory than a colorful scenery even if they have the same megapixels.

The term "megapixels" is simply a measure of how many MEGA (or million) PICTURE ELEMENTS, (or "PIXELS") there are that make up the photo. It's a simple multiplication of the number of pixels wide by the number of pixels high.
EXAMPLE: If your camera is set to shoot a photo 1600 pixels wide and 1200 pixels high you would multiply 1600x1200=1,920,000, or about 1.9 million pixels (megapixels) in the photo.

The term megabytes (or Mb) is in reference to the amount of storage space your photo takes up on your hard drive. Each pixel does not equal one byte, so it follows that 10 million pixels (or megapixels) don't necessarily require 10 mb of storage space on your hard drive. The JPEG format of saving photos also does a lot of compressing. The more similar adjacent pixels (same color, same texture) the more compression you get.

So although the more megapixels you have in the photo, the more megabytes you will need to store the photo, it is not a one pixel for one byte relationship.

Thats simple it most likeky the default to store the most picures on the memory card you can always chage the seting to take more dettailed shots but for every meg you go up in quality you lose the ability to be able to store as many new pictures so your camera that could take 500 pictures in 1.8 now can only take 60 or so in 14meg
so unless you profesional or Plan on making posters a compromize need to take place i sugets between 6-8megs and even a bit less if you doing 3x5 prints

Boy, this thread is loaded with allot of techno jargon, some of it useful, and some of it pure guessing, or nonsense.

Simply put, a camera Megapixel rating is a measurement of the cameras maximum image size (Width X Height) in pixels.

Megabyte is the memory used to store the image. This varies with file format, and content of the image.

Mega pixels is the density of the color of the photo eg 14 million per sqaure inch and megabytes is the size in your gard disc, in other words a photo of 14 million megapixels will take 3.2 megabytes of spce on your hard disc. I hope this helps!!

John; Mega is a numerical statement. Pixels are the dots used to make up a digit picture. Bytes are the amount of memory used to save the pixels. 1.8 megabytes is about the same memory space equal to one hole 3.5 inch floppy disc. So, if you were to put your pictures on floppy discs you could only fit one picture per disc. 1.8 megs is a large file for one picture.

Rich