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How does post photo editing affect file size?
Dear all,.

I am currently using a Fuji S6500fd and am days away from taking the step up to an SLR (Nikon D80)!.

I have a bit of a query with post photo editing..

Say for example a 6MP shot with my Fuji gives an average JPEG file size of around 3.2MB. If I run it through Google's Picasa2 software to enhance colours, crop etc. it reduced the file size right down to around 600KB. The photos looks fine on the computer screen, but then when I come to print them, anything bigger than a 6x4 looks horrendous..

I have just this morning invested in Paint Shop Pro X, and with the imminent delivery of my new D80 I am a little concerned than post photo editing will hugely reduce the end quality of the image..

My question is, how dramatically does editing photo's affect the overall JPEG file size and quality?.

If I'm taking 10MP shots with my new D80, how large should I expect to be able to print them AFTER I have dabbled with them using Paint Shop Pro X?.

Many thanks for reading, any advice or guidance would be greatly appreciated!.

Best regards.

James..

Comments (10)

The editing software shouldn't be reducing the file size unless you tell it to, the point of post production is to make the image look better, not worse. I have not used paint shop pro, but have heard that it is quite competent software, so you shouldn't have the problems you are getting now, alternatively you may be able to alter the settings in Pisca so that it doesn't resize the images...

Comment #1

I've been having this problem also, and can't figure out if I'm just the idiot or if it's something I'll have to live with..

For example: I have a photo that is a 2.5mb jpg file (300 dpi).

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

When I crop out the stuff at the bottom (cropping for 8x10), it takes the file size down to ~700k (still 300 dpi).

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

Still looks the same, and the crop will print fine for a 4x6, but a lot of times I want to go bigger and ~700k just doesn't cut it..

I have the D40 - is this something I'm just going to have to live with b/c of the 6mp? Should I learn to take my shots so that cropping isn't necessary?..

Comment #2

Photo Editing shouldn't affect file size. It depends how you save the edited image..

If you make the image physically smaller, it will have a smaller file size, obviously. If you change it from a TIFF to a JPG is will be smaller because JPG files are compressed. But if you leave the size alone and don't change the JPG compression, saving a JPG should not change file size much. It will a little because you changed the image a little..

File Types:GIF - non-lossy but only 255 colorsJPG - lossy and degrades with compresson %PNG - non lossy but not used muchTIFF - non lossy but not viewable on the Web.

When you save a JPG (of J-Peg) use "save as" then choose the amount of compression you wish. If you're going to print it, pick the highest setting (least compression). Also don't reduce the size much, just enought to fit the print size, at the most..

If you are going to put it on the web, I'd suggest around 600 pixels on the longest side and a 30%, or around that, compression. You want a file size to be under 100k or close. Most graphic programs supply a slider for choosing compression during the save process. They also usually show the file size as you slide the compression to more or less compression..

Don't print the image you saved for the Web and don't put the image you saved for printing on the Web..

I shoot in RAW. I then process and save images I intend to print as TIF (TIFF) files. I then lower the physical size to something like 650x400 pixels and save it as a 30% JPG. I then have two versiions, one for Web and Email and one for printing. I keep the RAW version around in case I might want to redo the composition later..

I have a short piece on Web Graphic located here:http://www.guidenet.net/resources/webgraphics.html..

Comment #3

There are two possible reasons why your saved file size has reduced so much after editing and saving in Picasa. The first is that Picasa has saved the JPEG file with severe compression. The more you compress a JPEG file the smaller the file size but the greater the loss of quality. This might have caused you quality problems..

The second and more likely cause of your quality problem is that you have cropped the image so severely there aren't enough pixels left to produce a decent print even at anything over 4x6..

To get a good print you need a resolution of about 150-300 pixels per inch (PPI). So for a 4x6 print you need a minimum (at 150 PPI) of (4x150)x(6x150) = 540,000 pixels and a maximum of 2.2MP. For a 10x8 you need a minimum of about 1.8MP and a maximum of 7.2MP..

I am sure that you can do the calculations for your D80.Chris R..

Comment #4

I've not used Picasa. But when you start with a 3.2MB file which after editing results in a 600kB file size, it has been compressed too much..

In Paint Shop Pro, when saving as a jpeg, there is an "options" button. There you select the amount of compression. Small numbers meen the highest quality. Around 5% to 10% is usually acceptable. If you want a small file for email etc., you could choose a higher compression value, perhaps 20% to 30%. At that level, the image quality is already degraded, but may be acceptable viewed on screen..

Photoshop Elements has a similar control when saving as a jpeg. The quality settings use different numbers, around 10 or 12 is the highest quality, lower numbers mean a smaller file but poorer quality.I assume Picasa has some similar jpeg quality setting..

Hope this helps,Peter..

Comment #5

Before making any changes, save the file in an uncompressed format, like TIF. Then every change can improve instead of degrade the image. Never make a change to a JPEG and press the "save" button. The file size is being reduced because you're saving a compressed JPEG as a compressed JPEG without any control on how much compression is taking place. Each save to a JPEG reduces quality and lowers file size..

It's important to set up a proper workflow that doesn't degrade your images..

Larry Bermanhttp://BermanGraphics.com..

Comment #6

Before making any changes, save the file in an uncompressed format,like TIF. Then every change can improve instead of degrade the image.Never make a change to a JPEG and press the "save" button. The filesize is being reduced because you're saving a compressed JPEG as acompressed JPEG without any control on how much compression is takingplace. Each save to a JPEG reduces quality and lowers file size..

It's important to set up a proper workflow that doesn't degrade yourimages..

Yes, don't save as JPEG repeatedly. Save the file in a lossless format before you start editing. BUT editing the file can't "improve" the image. Most moves you make in your image editing program will degrade it in other ways. It might look better, but your original JPEG is as good as it gets. Always keep this...



Suggested workflow: 1. your original jpeg, 2. your edited file in a lossless format (with photoshop you can keep all your edits in layers in photoshop format which is losslessly compressed) 3. your final edited file in various jpeg versions: for printing, web viewing, email, different crops... all generated from 2. your lossless edited file...

Comment #7

Dear all,.

This was my first post on this website and I'm absolutely blown away by the responses and great feedback & advice!.

Just wanted to say a big thanks for all the replies - I will definately be sticking with this forum!.

Best regards.

James..

Comment #8

I have noticed that sharpening an image in Elements V6 increases the size of the image jpg file.... anyone else noticed this?..

Comment #9

I picked up this thread late. I see that Peter has correctly analyzed your issue. Let me offer a summary:.

JPEG files are compressed. The level of compression is a variable. When you select "JPEG-Fine" in the camera, the compression level is low. This gives a high quality image. Different cameras have different "formulas" for how to encode their best JPEG files. Few of them are the same..

When you edit a file and resave it in the JPEG format, almost all editors allow you to select the quality level. However, their description of the choices of quality level/compression amount vary considerably!.

If you select the highest IQ compression level in most editors, you can even INCREASE the file size, compared with the way it came from your camera. Using these super-high/low compression JPEG formats allow you to save to JPEG a few times w/o noticeable quality degredation (contrary to what some pundits say). Don't worry too much!.

If you are a pro or a wacko amateur, then shoot in RAW and setup a workflow as suggested..

JPEG file size is also affected by the amount of detail in a pic. Prove this by taking a picture of the sky and then of the ground. The file sizes will be quite different. The sky has few small details, but the ground has many. The compression level of ALL schemes is affected by high-frequency detail and JPEG is not different in this regard. SO...if you sharpen a pic in an editor and then save it as a JPEG of comparable IQ level as the camera, the file size should be larger...because sharpening increases the high-frequency content.



BTW, any file format CAN be compressed, even TIFF and RAW. There are many different types of compression. There are entire books about various compression approaches! There are two basic types: lossy and non-lossy. JPEG uses a lossy scheme, thus the variability in size and IQ. Some cameras and editors give you the option of compressing their output files. For example, the Nikon D300 has an uncompressed RAW (NEF), plus a non-lossy compressed RAW and a lossy compressed RAW..

Hope all this helps further confuse you... .

Charlie DavisNikon 5700, Sony R1, Nikon D300HomePage: http://www.1derful.infoBridge Blog: http://www.here-ugo.com/BridgeBlog/..

Comment #10

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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