Having issues with my Evo pic quality. I'm shooting in 8mp setting, but pix always come out grainy. Also, files are never more than 2.4 mb and are usually under 2mb all together. Want a 2nd opinion before I go marching back to Sprint. Here are some shots taken with the 8mp setting (yes, I'm sure). The shot of the watch is with the front camera (default 1.3mp setting).: What I'm most concerned with is the file size of the pix. Should they really be under 2mb. My 10mp digital camera takes 10mb file shots. Shouldn't it be the same thing?
No it should not be the same thing. The word pixel comes from two works picture and element. A byte is a computer term describing a element of storage on a computer. There is not a one to one correspondence between a pixel in an image file and a byte in the storage location on a computer.
First off the Evo (and a whole lot of other cameras) camera takes pix by collecting photons using detectors (sometimes called wells) on the camera sensor (sometimes called chip). A first rate digital camera can have its detectors activated with as few as eight photons, but most need a lot more photons for the detector to record data. That data is flushed to buffers and the camera firmware creates a RAW file with croma and luma data from every detector. Since the Evo uses a Bayer sensor there is a RGB mask over the sensor and about 30% of the detectors are covered with a red filter, 30% a blue filter, and 40% a green filter resulting in many of the detectors having no data so the firmware interpolates what it thinks the data should be based on data from the surrounding detectors.The RAW file is then converted by the firmware into a file format that is easier to view, in the case of the Evo a jpg, which is stored on the sd card in the Evo.
A jpg file is what is called a lossy file which means every time you mash down on it using PS, or other editing programs, it loses some IQ (Image Quality). Additionally jpg files (and many other image file formats) use compression methods to shrink the size of the file. One example of this would be if you had a blue sky instead of this information being stored with the croma and luma data for each individual pixel the file would say something like the next 5,387 pixels all have the same croma and luma data.
Combining data compression used in jpg files and interpolation used by a Bayer sensor often results in significant differences between the number of detectors on the sensor, number of pixels in the image, and number of bytes in the image file created.
Just for the record a Bayer sensor camera has to have more detectors on the sensor than pixels in the image because the firmware needs to know what data is in detectors past the edge of the image so in can use that information to interpolate for detectors that recorded no information. In the case of the Evo's 8mp camera the jpg file produced has resolution of 3264 x 1952 Pixels or 6.37 MPixels
Here is a link that may be of interest
What is best way to PP jpgs - FM Forums
and one of my pix