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Archive 2014 · confused

  
 
aladyforty
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p.1 #1 · p.1 #1 · confused


I wanted to enter a photo in competition, it was from a 7D and almost full sized yet only 4.4 megabites. The image had to be cropped to 2200 on the longest side but was to be no less than 2 megabites. after resizing in several programmes it would only show 1.5 MB so I could not enter it. Yet a more heavily cropped photo (not the one Im talking about) had higher megabites. Im wondering what effects the photo that makes it less or more megbites. I have photos taken with my 10 megapixel showing more megabites and my 18 megapixel 7D.


Apr 27, 2014 at 06:44 AM
Dave_EP
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p.1 #2 · p.1 #2 · confused


Megabytes has no relation to resolution, it's generally a function of the file format.

A 2200 pixel TIFF file will be bigger (file size) than a 2200 pixel JPEG, so check carefully what file format they are looking for. Maybe that's the key?

Also, set the quality to 12 for JPEG in Photoshop and you'll get a much bigger size than if you picked quality = 8.




Apr 27, 2014 at 07:13 AM
verbiage
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p.1 #3 · p.1 #3 · confused


To add to Dave's response, sharpening can be a factor, and also the ISO (higher ISO usually means bigger file size), but most importantly, how much of the image is in focus. Other things being equal, afisheye shot at F/8 - F/11 will produce a much bigger file than would a bright portrait lens wide open, with only part of the frame in focus and the rest a nice blurry background.

These factors can have a fairly significant effect on file size, but not so great as jpeg quality or file format (tiff vs. jpeg).



Apr 27, 2014 at 07:35 AM
James_N
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p.1 #4 · p.1 #4 · confused


It depends on the content of the image. If you're taking a scenic photo which contains a lot of sky you can expect the file size to be smaller because there's aren't many details in skies (or a blank wall for that matter).

Then you have to consider the effect of compression; files with less details will be compressed more than files with plentiful details and this causes smaller file sizes.


aladyforty wrote:
I wanted to enter a photo in competition, it was from a 7D and almost full sized yet only 4.4 megabites. The image had to be cropped to 2200 on the longest side but was to be no less than 2 megabites. after resizing in several programmes it would only show 1.5 MB so I could not enter it. Yet a more heavily cropped photo (not the one Im talking about) had higher megabites. Im wondering what effects the photo that makes it less or more megbites. I have photos taken with my 10 megapixel showing more megabites and my
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Apr 27, 2014 at 07:46 AM
Monito
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p.1 #5 · p.1 #5 · confused


aladyforty wrote:
4.4 megabites [...] 2 megabites [...] megabites [...] megbites [...] megabites


megabytes

A byte contains 8 bits (ones or zeros) and represents a number from 0 to 255 or from -128 to +127, depending on interpretation. It can also represent one alphanumeric character in the common Western character sets (mainly English).

Your question has been very effectively answered by Dave_EP, verbiage, and James_N above. The three responses address different aspects.



Apr 27, 2014 at 08:05 AM
Alan321
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p.1 #6 · p.1 #6 · confused


ISO matters primarily because of increased noise that usually occurs at higher ISO; it is not the ISO itself. As camera sensors improve the the extent to which higher ISO matters is gradually reducing, and these days there may be very little between ISO 50 and say ISO 800 in terms of jpg file size.

Noise reduction can shrink an image file size considerably, especially if it is over-done.

- Alan



Apr 27, 2014 at 10:30 AM
John Wheeler
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p.1 #7 · p.1 #7 · confused


Hi aladyforty - I am going to take a different approach on this.

Given that you are in western Australia I will assume that you want to enter the Canon Click West competition which appears to have the same rules you mention.

The "rules" they mention also have another page that indicate they are not so strict on that lower limit of 2,000 KB. Just look under the Rules dropdown and the last link is "File Size Rule":

http://www.clickwest.com.au/index.php/rules/file-size-rule

Along with the "This" typo in the rules here is what is said:

his is a guideline and smaller file sizes will be accepted ( however if the file size drops to far the image quality may suffer)

Good thing as well because I took a 1:1.5 aspect raw image I had handy, made the long dimension 2200 and then saved at quality level 12 in Photoshop and it came out 2.2MB so it would be very easy to drop below 2MB

From my understanding and their example they did want JPEG images in sRGB color space so this is not a format issue such as submitting TIFF files (given my contest assumption is correct).

One note however, if at all possible, I suggest it would be best to take images in Raw and then go to JPEG a final post processing (if you are not already doing this). The in camera JPEG compression followed by bringing it into a post processor and then recompressing can reduce overall quality. Just a suggestion and hope the above information is helpful.




Apr 27, 2014 at 01:17 PM
aladyforty
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p.1 #8 · p.1 #8 · confused


Thanks for all the feedback. Image was shot RAW, converted to a 16 bit tiff. Edited in PS then converted to jpeg. I saved largest size but still did not work. They would only accept jpeg. The image was a macro of a small beetle on a pale flower and the beetle was the only thing in focus


Apr 27, 2014 at 11:31 PM
postpicspls
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p.1 #9 · p.1 #9 · confused


With JPG compression, the amount of detail will affect the file size. An example is if you take a photo of an image with a gradation or lots of flat color, it will compress the file more than an image of the same size with LOTS of detail such as leaves or feathers. JPG looks for areas it can throw out redundant data like large blocks of color. If you sharpen an image it will generally not allow as much compression.

Keep in mind, files of the same format, i.e. .tif, .jpg, etc., saved from different programs may end up being different sizes. If you use Photoshop to make a JPG make sure you pay attention to the quality. 12 is the highest in Photoshop and therefore the "best".



Apr 28, 2014 at 09:27 PM





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