Saving Images At Different Sizes

[Harold Gough]

I was recently concerned that resizing for posting from a large JPEG file was losing some detail compared with the same manipulation on a smaller JPEG file from the same Raw file, both converted by the same software.

http://www.photomacrography.net/forum/v ... 245#126245

I use Irfanview to save my 4032 x 3024 RAW (ORF) files as JPEG. The default size, for ORFs, is to save as 3200 wide. I use to do that. then someone here, wanting to get the full information about an image being discusses, asked me to save at a larger size. Since then, I have always saved at 4206 wide.

Recently, I saw some loss of detail when cropping images, and resizing to upload, from the large file compared with the default size. Since then I have saved at the smaller size and any posted images are from such files.

This is an exercise to look at this for an image (female Orange Tip butterfly) with some fine detail. Here are 4206 and 3200 version, processed in the same way and crops from those images, in each case process from the cropped original but identically.

I no longer see a clear difference. If there is little to chose between them I could save significant time in saving them as JPEGs.

The lens was my iron 105mm macro at 1/125 f8 ISO 800, hand-held, overcast.

4206



3200



Crops, 4206 L and 3200 R:



Opinions, please.

Harold

[rjlittlefield]

The images on the bottom of the first pair and the left of the second pair have way more noise, especially in the background. This is odd because the corresponding labels are "3200" and "4206".

I agree there's not much difference in detail resolution.

--Rik

[Harold Gough]

Thanks, Rik.

I noticed the same difference in the noise level. I have just re-run processing and get the a same difference, although I would not like to say how different the noise levels are. However, that, alone, is against saving to a large size.

Incidentally, when I post the image in the gallery I may go for slightly less processing.

Harold

[rjlittlefield]

However, that, alone, is against saving to a large size.

I read it as saying that there's something fundamentally flawed about the workflow and/or tools and/or parameter settings that you're using. But from just what I'm reading and seeing, I can't tell what.

If you'd like to email me the ORF, I would be happy to take a look at the situation. Address is rj.littlefield at computer.org .

--Rik

[Charles Krebs]

Harold,

Are you using IrfanView to simply "pull" the imbedded jpg file out of the raw (ORF) file or are you actually using a plug-in to have the raw data processed?

In IrfanView check: "Options > Properties/Settings > Plugins"

The default choice is to simply try to pull the imbedded jpg file out of the raw file. While this is the fastest way of viewing the picture subject matter for a quick look, it is not what you want for quality results.

I'm confused by the pixel dimensions you are providing. What camera are you using?

[Harold Gough]

Charles,

My version of Photoshop can't even see ORFs let alone open them.

I was dissatisfied with Olympus Master 2 for opening ORF RAW files and saving them as JPEGs. At some stage I was advised that IrfanView did a decent job of that. I know nothing of plug-ins for Irfanview although I use them in Photoshop.

IrfanView saves files in a huge choice of formats, of which JPEGs seems the most useful. I had no reason to doubt that this was a good thing to do.

I never do anything in Irfanview exept for a quick look and always save as a JPEG from the original ORF file.

I have checked "In IrfanView check: "Options > Properties/Settings > Plugins" and am no wiser.

The camera is an E-P2 m4/3 and I shoot only RAW.

Harold

[Harold Gough]

I know nothing of plug-ins for Irfanview although I use them in Photoshop.

That is not quite true. Essentially, IrfanView would not function (I can't remember the details) without its plugins.

I just downloaded and installed them again, just to be sure, and still don't see the issue. I don't see any way of doing things differently in saving ORF files as JPEGs.

Harold

[Charles Krebs]

Perhaps I do not fully understand your "problem" but it sounds to me like you may not actually be processing your raw files but merely extracting a jpg file that is imbedded in the raw file.

In addition to the raw data, raw files typically will also have, "imbedded", a jpg of the image. This is really meant primarily for a quick preview of the picture. Otherwise, to see the picture, it is necessary to run the raw data through a conversion program which can take a bit if time to process. This is fine if you know you want to keep the picture and want the advantages provided by using raw files. But it is a pain if you are just trying to edit down a large number of shots to find the "keepers" and delete the ones you don't want.

if you choose to process the raw data, IrfanView (and quite a few other programs) can internally use use an open-source raw conversion program called "dcraw" (written by Dave Coffin). However, the "default" situation in IrfanView is to simply pull out the imbedded jpg from the raw file. (Which is why I suggested you check the plugin options). This is no better, (and quite possibly worse) than simply shooting a jpg to start off with.

Since jpg is a lossy image format, if you want the best image quality you should properly process the raw file and then save the image as a "tif". Then, after and editing and resizing for the web or email go ahead and save it as a "jpg", but keep a keen eye on your compression amount (sometimes called "quality setting").

Your camera sensor provides images that measure 4032 x 3024 pixels. So I am not sure why you are saving them at 4206 pixels wide. The raw image should also process into an image measuring 4062 x 3024 so again I do not know why you say that... " The default size, for ORFs, is to save as 3200 wide"... unless that is the size of the imbedded jpg.

[rjlittlefield]

I don't see any way of doing things differently in saving ORF files as JPEGs.

The main issue is not how the image gets saved, but rather how it gets read in the first place.

The default is to just reach into the .ORF and pull out an image that the camera created by doing a rough-and-ready raw conversion and JPEG compression inside the camera. All the actual raw data is ignored by IrfanView in that case. This makes the load into IrfanView very fast, but the quality suffers. What you want to do is change the options so that IrfanView does the raw conversion itself, using the greater power and smarts of the PC instead of the camera chip.

Here's how to make the change...

Go to Options > Properties/Settings > Plugins and remove the checkmarks on "Try to load embedded preview image" and "Load half size image". OK to close the dialog.

After that change, load an ORF file. Assuming you have the proper plugins loaded, the image will open successfully, but it will take a lot longer than before. That's because IrfanView actually had to do the raw conversion, instead of just reaching into the raw file and pulling out an already converted image.

You can further confirm by changing the Brightness setting to a value of 0.5 (again at Options > Properties/Settings > Plugins). OK to close the dialog, then File > Reopen. Again there will be a long delay, and when the reopen is complete, the image will be a lot darker than it was before. That's because the raw file was re-converted using the new value for Brightness.

--Rik

[Charles Krebs]

Additionally I will add that if you really want to get the most out of a raw file you really should use a processing program that allows you to make adjustments to the processing parameters. Things like color balance, exposure, tonality adjustments and such.

I don't know why you were dissatisfied with Olympus Master 2, but there are other, free, alternatives (UFRaw, Raw Therapee... and more) that provide some control over how the raw data is processed. It's pretty hard to realize the benefits of shooting raw files if you have a program that only does a basic "generic" conversion.

[Harold Gough]

Rik and Charles,

Thanks. I did what Rik suggested and it certainly slows it down.

I have re-saved and reworked two images with the re-set Irfanview. There seemed to be more detail and the noise was more clearly defined and perhaps less of it and less damge to the actual JEPGs. I need to check whether these differences are real.





The butterfly has fewer highlights burned out than in the previous version, the first image in the topic.

I abandonned Olympus Master 2 because it was even slower than the reset Irfanview and any images I moved to different folders, or backed up, were unreadable due to broken links, each image needing to be re-linked. IrFanview has no such problem.

I use Photoshop to adjust brightness contrastand colour balance and to resize for uploading. I use Topaz plugins, in PS, for NR, focus, micro contrast and (when needed) shadow light.

Harold

[Charles Krebs]

Harold,

I need to check whether these differences are real.

They should be very real! If you have been using the imbedded jpg's then you are in for a treat when you start converting some of these files with conversion software that allows for certain "corrections".

You do not mention which version of Photoshop you are using. Can you let us know? If it is a matter of your camera coming out after a more recent version of Photoshop became available, then there is a method that you can use. (As long as your version of Photoshop is not so old that it does not recognize any raw files at all. Raw file capability will be with Photoshop CS (or v8.0) and newer. CS came out in 2003). Adobe did not go back to older PS versions and upgrade the raw conversion section ("ACR") for newer cameras. But they do provide a free conversion utility known as "Adobe DNG Converter". This utility is regularly updated with the newer cameras. It will convert all raw files, from all the cameras supported to a common raw file format ".dng". This format can then be read and opened by any version of Photoshop that can read and convert any raw formats at all (CS and newer). It is an extra step, but it is actually pretty painless once you set it up. You simply run the "OCR" files (singly or as a batch of files) through the converter and it creates and save a new file with the ".dng" extension. It is available in both PC anf MAC versions. Here's a link for the PC version:
http://www.adobe.com/support/downloads/ ... rm=Windows

If your version of PS is older and can't read any raw files at all then you should maybe take another look at the Olympus Master 2 program. (You can get the latest version by running the program you now have, going to the "Help" tab, and then selecting "Update Software"). Or you can take a look at some of the free conversion programs like the ones I mentioned earlier. Some of these use the DCRaw code I mentioned earlier, which is used internally by IrfanView. But they provide an interface that allows you to make some important adjustment to the image while converting from raw. For a free raw converter program Raw Therapee is very nice. It can get pretty involved, but if you stick to basic exposure, color and tonality settings it is not overwhelming. I think you would be very pleasantly surprised how much highlight detail can be salvaged from a shot like the initial butterfly example you posted here.

A logical way of working is to use a program such as IrfanView set up so that it reads the imbedded jpg for a quick, initial look at the pictures you have just uploaded. Delete the ones you don't want and then convert the "keepers" to Adobe .dng for processing in Photoshop.

Again, if your Photoshop version can't do any raw files, forget about the .dng conversion and use one of the other programs we have discussed.

[Steve S]

Harold, as a long-time lurker on this wonderful site I know how much time you put into this, and for the sake of your time and the honor of your Apo Componon, you should rethink your processing practices. I second everything the redoubtable Rik and Charles have said, but would like to add a few details.

The “noise” in the 4206 crop in your original post looks very much like JPG artifacts; if you blow it up to 400% in your browser you can almost see the little Fourier worms wiggling.

You really should think of JPG as a format for certain types of output and for casual use, and not as a general-purpose intermediate processing format. One reason is that any change to the image and resaving results in further loss of detail and compounding of artifacts, but that is only one reason. Equally important, your raw image contains 3X12 bits of information in each pixel, and a conversion to JPG immediately reduces that to 3X8 bits. In effect you are throwing away a third of your information before proceeding to adjustments in Photoshop. Among other things, this can lead to color “banding” such as is seen in the flower filaments in the upper left of the photo of the multi-lobed stigma.

I sympathize with your frustration with the slowness of raw conversion, but the time it takes is a small fraction of what you put into this. Try making basic adjustments in a good raw converter, and saving to TIFF (or go the DNG route) for those things that need to go on to Photoshop. Or make a modest investment in Adobe Lightroom, which provides extensive raw adjustments, great convenience in comparing raw images, reasonable retouching facilities, etc. If you want to print, usually you can do that right in Lightroom, with no need to create an intermediate file and go on to Photoshop.

I regret recommending an Adobe product right now, in the midst of the infuriating Creative Cloud revolution, but Lightroom is another matter.

Steve

[Harold Gough]

Charles,

I have downloaded the Adobe DNG .exe (latest version) and can't get it to launch. There is some problem with my PC which apparently needs a Disk Check so that may be the problem. Everthing is desperately slow at the moment. I will run it tomorrow as it takes hours.

I have PS 7

Harold

[rjlittlefield]

Equally important, your raw image contains 3X12 bits of information in each pixel, and a conversion to JPG immediately reduces that to 3X8 bits.

Minor correction... Raw format is actually 1x12 per pixel position. Each pixel position gives a 12-bit sample of only one color, R or G or B depending on position within the Bayer filter array. The conversion or "developing" of a raw image is what fills in the other two colors based on some sort of interpolation. A large part of the PC's advantage over the camera for raw conversion is that the PC has more time and horsepower to do good interpolation.

--Rik