How much cropping without affect photo quality?


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pop

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Me using FX9, 6MP camera. Suppose I want to just crop a part of the shot for developing into photographs, say 4R size. How much can I crop away so that the remainder is still good for developing into 4R? Is there a rough guide? Like maybe if I crop away 75% and remains 25% still ok?

Then if I'm using PS, when I save the resulting work into a jpg file, do I need to save at maximum quality, ie, 10?

Sry, newbie in learning mode. Thanks in advance.
 

oeyvind

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#2
u can crop as much as u want... 4R is roughly 1600 x 1200 pixel at its best quality. So, just crop them see at 100% if it will hold for your eyes, then it will.... there's no formula, it's look and see.
 

#3
pop said:
Me using FX9, 6MP camera. Suppose I want to just crop a part of the shot for developing into photographs, say 4R size. How much can I crop away so that the remainder is still good for developing into 4R? Is there a rough guide? Like maybe if I crop away 75% and remains 25% still ok?

Then if I'm using PS, when I save the resulting work into a jpg file, do I need to save at maximum quality, ie, 10?

Sry, newbie in learning mode. Thanks in advance.
25% wont leave much, printing quality will fall for prints above 4R

with 6MP i would try to leave at least 3MP or more after the crop, can check this by multiplying the pixel dimensions after cropping and divide by 1,000,000. e.g. 3008x2000= 6,016,000 / 1,000,000 = 6.016MP

but if your not printing or submiting for stock or posters etc then can crop as much as you want!
 

#4
To crop 75% of 6 megapixel image will seriously degrade image quality. You can attempt to resample the image up (re sizing image) ; but the results will depend on what software you are using and how detailed the subject matter. There are specialist programmes which claim to work but I’ve no experience of them. Iwould welcome any feedback from anyone who has used them.

A 25% crop is just abut the limit for a 6 mp camera. You could produce a decent 18x13 print with that and you could push to A4 with resampling. You will not get anything larger than an 10x13 print with 50% and a 75% crop will only be good enough for 6x4

Ideally you should resize images to 300 dpi for print.

To get a decent 18x13 print the size should be 3megapixels or 50% of your 6mp image.

Going to 75% crop will mean 6x4cm is the best you can do at 300dpi

With larger prints A3 or more you can get away less resolution (200dpi) as the pictures are viewed from a greater distance. A smaller image will be looked at more closely so the 300dpi is best exceeded.

Another important thing to remember for the beginner is that every time a JPEG image is saved the quality will be reduced. Always keep a copy of the original and work from that. Even rotating image using windows Explorer will save a reduced JPEG without the user knowing. I was caught out by this when I first ran Win XP!.

If you think an image will need a lot of work and you have Photoshop Elements or CS2 save as PSD or TIFF file, you can save this many times without image degradation.
 

pop

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wow, there's a lot of science to this. Thanks guys for enlightening.

yes, I meant to crop a part of it, like say, 25% of the shot, and then send this 25% to make a 4R print.

Dave, by saving to psd, can the processing shop print it? I always thought a picture file will need to be in jpeg?

thanks again for helping with my query.
 

theRBK

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May 16, 2005
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#6
Saving to PSD or TIF is for your own archiving... for printing, to avoid grief, just give them a minimally compressed, in PS say compression 10, Jpg...

Also, how much you can crop depends on the sharpness of the original shot... there are no hard and fast rules...
 

solarii

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#8
If in doubt, you can consult the guy doing the printing if he's friendly. For me, I'll usually ask the guy to take a look at the file and advise. As theRBK has mentioned, the sharpness of the shot matters a lot (ie quality of the lens). The resolutions recommended are only guidelines... you can stretch the "limits".

Also, crop the file to the size ratio you'll be printing in. ie 4R crop to 3:2 ratio.
 

spurssy

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May 27, 2004
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pop said:
wow, there's a lot of science to this. Thanks guys for enlightening.

yes, I meant to crop a part of it, like say, 25% of the shot, and then send this 25% to make a 4R print.

Dave, by saving to psd, can the processing shop print it? I always thought a picture file will need to be in jpeg?

thanks again for helping with my query.
Depending on the quality of the original shots, sometimes 25% of a 6mp still looks ok for a 4R print (remember what you see 100% on screen is always sharper than a print). I do that sometimes... for example, when I'm shooting a very far object and my zoom is already at maximum.. so bo bianz... just remember, 100% = good print, 25% = average print, BUT.. average print is still better than NO PRINTS!

Well, the abovementioned may not work if you're quality conscious...

BTW, if you ever want to save a JPG for archive in PSD, you can save yourself some storage space by:
1. Removing any layers that you don't need!
2. Flatten any set of layers that you will definitely not change...
3. Turn off the option of "Maximise compatibility" when you save a PSD

The above steps sometimes shaves half of my storage space.
 

theRBK

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May 16, 2005
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#10
spurssy said:
BTW, if you ever want to save a JPG for archive in PSD, you can save yourself some storage space by:
1. Removing any layers that you don't need!
2. Flatten any set of layers that you will definitely not change...
3. Turn off the option of "Maximise compatibility" when you save a PSD

The above steps sometimes shaves half of my storage space.
or you could save in compressed tif...saves even more space while keeping all the layers...
 

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