Post-processing RAW Files - ACR Compared to Some Free Software Options

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Post-processing RAW Files – ACR Compared to Some Free Software Options


What is RAW?

Title-imageA RAW file is really the digital negative, which means that all the data is stored waiting to be unleashed via a RAW Editor. Unlike a jpeg file which has been edited in-camera (or in post-processing) and is a compressed 8-bit file.

Why shoot RAW?

The main benefit to shooting RAW is simply to have as much information as possible in the file. When you upload a RAW file onto your computer the white balance, and tonal corrections have to be set manually. More detail can be retrieved from the highlights and shadows. It is then saved as a jpeg or some other format. The RAW file always remains in its original state.

Shooting RAW has become more commonplace as cameras have the option, built-in and RAW editing software is more widely available on both Mac and PC. In this article, I will be testing out two RAW editors which are free to download. Yes, no purchase necessary. The main RAW editor that I will go into more detail on is Adobe Camera Raw (ACR), which comes with Photoshop and is my primary go-to RAW editing software.

As a side note, this article is by no means a complete in-depth review of the pros and cons of each of the the three RAW editors. I merely wanted to test Photoshop’s ACR against some of the RAW editors that are available to download for free, such as GIMP and RawTherapee.

A few years back, I was using ViewNX (now ViewNX2), which is Nikon’s RAW free editing software. Canon (DPP) and other major camera manufacturers have their own RAW proprietary software. But I found ACR just got better with each new release. I usually bring my images into Photoshop when I’ve done the initial edits in ACR. It means my workflow is quite efficient as I’m using ACR and Photoshop side-by-side.

The Basics

When you open ACR or any RAW editor, the user interface can be a bit daunting for the uninitiated. The range of adjustments and all the features of ACR would require several articles alone.

So, let’s look at the basic adjustments where I begin the editing process of my RAW files. These adjustments are fundamental to any RAW editor. Similar adjustments can also be found in the Develop module of Lightroom and in Photoshop Elements 12 and 13. Let’s begin with Adobe Camera Raw, otherwise known as ACR.

Adobe Camera Raw (ACR)


The interface when a RAW file is opened in ACR

When I open a RAW file in ACR, White Balance is my first port of call. This is about the color temperature of the image depending on the light source. If the white balance is incorrect, then a color cast will occur on your image. It may look slightly blue, orange or green.

The 3 important focus points in the Basic panel in ACR

The three important focus points in the Basic panel in ACR

In ACR, there are three ways to adjust White Balance.


Three ways to edit White Balance in ACR:
1. White Balance Tool
2. Presets
3. Temperature and Tint Sliders

  1. The White Balance Tool is my least favourite. The idea being that you click anywhere on the image that is suppose to be gray. I find this tool hit and miss.
  2. There are number of presets that are worth experimenting with, if you are new to RAW editing. Try Auto which is a good place to start.
  3. You can then adjust the Temperature and Tint sliders for finer tweaking and control. I favour these two sliders the most in my workflow.

Just above the Temperature and Tint sliders, you have the histogram panel. Click on the the two black triangles. These indicate the highlight (left) and shadow (right) areas that have been clipped (see photo below). As you can see in this image, the areas highlighted in red indicate where the clipping has taken place in the whites. Similar to the shadows, blue indicates where the shadow areas have been clipped.


Highlights-shadows-clipping in the Histogram.

When adjusting the White and Black sliders keep an eye on the black triangles in the Histogram chart. These triangles turn green when clipping occurs. Alternatively, you can hold down the Alt key while dragging the Blacks slider across to the left until the darkest area of the image starts to appear. Similar for the Whites slider, hold down the Alt key and drag the slider to the right until the brightest part of the image begins to show.

I tend to leave the Exposure slider until after I have adjusted the Highlights and Shadow sliders.


Exposure and Contrast sliders.

The Contrast slider gives your image that final punch but go lightly.


Final edited image from the basic adjustments in ACR

All edits done in ACR are non-destructive. Editing RAW files can be easily done in one pass, especially if you have captured the image that you want in-camera. However, there are no layers in ACR or Lightroom, so if you need further editing where layers are required you will need to use Photoshop or GIMP.


So this brings us to the next RAW editor, UFRaw. This comes pre-installed in GIMP, version 2.8. I’ve never used GIMP before now and I was really curious and enthusiastic to try it out. It has the reputation of being as powerful as Photoshop for editing – and the fact that it is free, is a bonus.

I presumed that by opening a RAW file that the UFRaw editor would launch automatically. It didn’t. After a quick research online. I found a solution. I had to go to File>Open>Select file. I then had to Select File Type and scroll down to the bottom of a list and click on ‘raw image’. Once I opened the image in question. It did not resemble anything like the image I had taken on the day. Normally when I launch a RAW file in ACR, it would be similar to the jpeg version.


The UFRaw editor does not launch automatically. A few clicks gets you there.

The interface was completely alien to me, and I didn’t find it particularly user friendly. I played around with the sliders for awhile but I couldn’t get the image to look right at all. I tried adjusting the White Balance but I couldn’t get rid of a green/grey color cast on the image. By not having the familiar sliders in ACR, I was a bit lost to be honest. I really wanted to like UFRaw, as it is a free software for Mac and PC. To be fair, this was my first attempt at using the software, so I’ll put the mea culpa (blame) on me as opposed to the software.


The UFRaw editor UI in GIMP


Now onto RawTherapee. I love the name. I wasn’t expecting much after trying out GIMP’s UFRaw but I was completely surprised and impressed. RawTherapee is available in 64 and 32 bit forms for Mac OS X and Windows. It also supports a huge range of supported cameras and manufacturer filetypes.


RawTherapee interface

This RAW editor is quite rich in features. Even so I found the user interface very intuitive, and after a few minutes I felt right at home. I quickly adapted to the menu system and found it very easy to navigate around. The editing panels are on the right.


Highlighted adjustment sliders that are similar to the ones in ACR.


If you haven’t edited a RAW file before, I would highly recommend that you try it out. The options are varied whether you decide to purchase Lightroom, or choose to pick from the many RAW editors that are free to download. The choice is really up to you. Another free RAW editor that has just been launched is Affinity Photo and it looks really promising (currently in beta for Mac only).

Read more from our Post Production category

Sarah Hipwell is an independent professional photographer based in Dublin. She specialises in high-quality corporate, stock and portraiture photography. Her background is in Design. She received her BA in Hons Design from the University of Ulster, Belfast. She has many years commercial design experience working as a designer and as a trainer for large multimedia companies. See more of her work at or at 500px.

  • How about Linux user?
    On Linux there are several great raw editors: Darktable, RawStudio, Photivo, Lightzone, UFraw, Fotoxx. PhotoFlow… RawTherapee works also on Linux.

  • sillyxone

    Too bad DarkTable is not abailable for Windows yet. I’ve been using it for over a year on Ubuntu, the workflow is just seamless, can’t hardly tell if I’m working with RAW or JPG.

  • bart9h

    I used UFRaw for years, it works well. The only thing I missed from it is a sharpenning control.

    Then I switched to Darktable, which is really awesome.

  • ????? ????? ??????

    thanks a lot

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  • Pro Photographer

    Spam. Spam. Spam.

  • Pro Photographer

    Acr is and always will be my choice. πŸ™‚

  • Iliah Borg

    Dear Sarah,

    Only raw is a positive image πŸ˜‰ One may call it a latent image, but negative is… well, it is not.

  • Chris Sutton

    Just wasted an hour with Rawtherapee – not intuitive at all (for an ACR user), bewildering array of adjustments with incredibly complex titles/names and resolutely refuses to transfer images to PS to finish editing (despite trying a variety of commands in the setup option).

    Really not worth the effort if you have ACR available

  • Sarah Hipwell

    Dear lliah, Thanks for your comment but I described a RAW file as a ‘Digital’ negative which is similar to a film negative;-)

  • Sarah Hipwell

    Hi Chris, with such a bewildering array of different RAW editors out there. Some more intuitive than others, I found RawTherapee more intuitive than GIMP. I’m sure many users of GIMP would disagree. There is a steep learning curve when trying out different applications and yes, it is a personal choice in whats suits you may not suit others. Thanks for your comment Chris.

  • Iliah Borg

    Dear Sarah,
    Raw has no features of negative. One does not need to invert it, instead, one needs to develop it, while a negative is already developed. Undeveloped image in photography is called latent image.

  • Tomas Sobek

    One more vote for the excellent Darktable! I used RawTherapee in the past but find Darktable even better. Thanks for giving free-libre software some well deserved coverage. I am always amazed how many people are stuck with proprietary software and mindset πŸ˜‰

  • Lamonte S.

    I think Digital Negative is a fair comparison to a RAW file. Ppl that have no training with film probably don’t know or don’t think about inversion & the sort, but only know that a negative has to be processed for a good print. So goes the RAW file. Iliah Borg, maybe you should write an article on the processing of film. Oh wait, this is “DIGITAL Photography School”. I’m just joking around, but seriously, lighten up. I’m sure Sarah Hipwell’s analogy confused no one.

  • Iliah Borg

    No, it is not fair. And it is unnecessary in “DIGITAL Photography School”.

  • Klaas Vaak

    Lightzone is available for Windows and also worth considering

  • Klaas Vaak

    It might be,, but do you really need to point it out? It is a bit pedantic; everybody understands and is OK with the comparison, as it is based on the functional aspects, as something that still has to be “developed”, not on a literal interpretation.

    And perhaps also interesting, are you SURE the encoding of the light values in a raw file is a simple positive linear function of the light values?
    Perhaps the engineers chose an inverted relationship, that would make it a digital negative.
    Is it even linear? Maybe they chose a wildly different encoding, like BCD, then it would map to nothing from the wet-chemical era of photography :).

  • Iliah Borg

    Yes, it needs to be pointed out as misnaming things cause a lot of confusion down the road. Negatives do not need to be developed, they are already developed. On the contrary, latent images need to be developed. These 2 things, positive image and undeveloped image, are quite enough – or we will start calling day a night only because on the other side of the globe it is night.

    The coding is irrelevant, what is relevant is the data itself. It is impossible to apply white balance to non-linear data the way raw converters apply it. So, yes, raw data in all consumer cameras is linear after decompression. The sensors that have photovoltaic response are not yet used in consumer cameras.

    You can look into any open source project dealing with raw data to see how the raw files are handled in terms of white balance.

  • Richard Leonard

    As an Ubuntu Linux user I’m happy to see some air time given to Gimp and other free photography tools. I use Gimp and UFRaw, mainly because they had the highest ratings. I find Gimp to be more than adequate for everything I do and I’m still finding new features. UFRaw is great, however I do find that even after fiddling with exposure and colour balance I occasionally need to adujst the Gamma to get the colours right. Interesting to see that other programs are recommednded by people on here. I must check them out. What I really would like is a noise reducer that doesn’t soften the image too much. Could be asking too much, maybe. Or I need to experiment more. Or upgrade to a better sensor…
    Just to clarify what may or may not be obvious to some people is the description of JPEG being an 8-bit file. Saying something’s 8-bit makes it sound really 1980’s. This is 8 bits per colour channel. That’s 24 bits per pixel, which is approximately the most that monitors and print can display. You really don’t need more than this. Not sure but I believe a RAW file contains 12 bits per channel (can anyone confirm this?) so that’s part of the reason you get more room to work with. When you hear 32-bit colour, there are the 24 bits for RGB and 8 bits for the alpha or transparency channel. Useless in photos but good when working with layers or for producing PNG files with non-rectangular images with transparent areas.

    Now someone’s going to mention Adobe RGB and quantum dot displays…

  • I’ll second that. RawTherapee is good, but Darktable is so much better. It’s available on Apple systems, though I use it on Mint Linux.

  • Lamonte S.

    lol. It doesn’t seem like photography or anything else relaxes you. My previous reply began with, “I think”. Am I not entitled to my opinion? Of course I am, just as you are. So therefore, I, and lots of others, think a negative & a RAW file are fair analogies. Why? b/c most people don’t think of a negative as an inverted image, which it is, but they think of it as something that has to be processed for a good print. That is exactly what has to happen to a RAW file. Since DPS is geared toward digital photography & fairly newcomers to the game, I would bet that most readers here don’t know much about negatives except for the previous statement. You may not agree with any of that, but that’s ok b/c you are allowed to have your opinions, too. Understand that I am not refuting what a negative is. I am just saying that I believe the analogy works for most DPS readers. Another opinion I have is that you are WAAAY too sensitive about the word negative. Try taking pictures of kittens & puppies. They usually calm people down. πŸ˜‰

  • Iliah Borg

    Of course you are entitled to your opinion, even if it is a wrong one. Sad you feel like one needs to distort the meaning of terms, especially to terms that you claim are foreign to the audience. The analogy to an unknown and not fully understood term works? That’s a good one πŸ™‚

    Negative is a red herring in the discussion of raw converters, and does not pass pluralitas non est ponenda sine necessitate.

  • I use Lightroom. I was just wondering why you didn’t mention Lightroom in the article?

  • Albin

    A bit odd to compare ACR, which is not “free” in any conventional usage, requiring purchase of an Adobe product. RawTherapee is quite well documented, unlike UFRaw – both the online “Rawpedia” and PDF manual for it are thorough. I’ve used it for several years, and the recent versions are pretty impressive. Big convenience to have the same software on machines dual booting Windows / Linux.

  • Lamonte S.

    lol. you’re still at it. smh. What I said was, most see a negative as something that has to be processed. I didn’t say that they have no clue that the word even exist. That makes the 3rd time I’ve said that. Surely you should have picked up on that since you can quote from friar William’s work on Quaestiones et decissiones in quattuor libros Sententiarum Petri Lombardi. As well, you should know that opinions are neither right nor wrong. If an opinion can be proven, it becomes fact. What Sarah wrote in this article has helped some people. If it doesn’t help you, so what. Keep it moving. You should write an article about why a RAW file is not a digital negative & see how many people you will help. Now we can go back & forth forever, but I will stop here & look forward to your next response so that you can have the final word. Since it bothers you so much & you seem to have to prove your point, maybe my next statements will help you through your day. You are right & I am wrong. You are big & I am small & there is nothing I can do about it. lol I bid you good day.

  • Iliah Borg

    Negative is not something to be processed, it is a wrong thing to say so.
    Raw data can be developed many times with different parameters, which is unheard of in film photography; while negative is (literally) a fixed object.
    As for my articles, try Google.

  • Try Darktable – for me best RAW editor for Linuks

  • Sarah Hipwell

    Hi Amit, I don’t use Lightroom but from what I have seen it appears quite similar to ACR, as it is developed by Adobe. I’ve just downloaded Lightroom 5 to try it out. Watch this space. Thanks Amit.

  • Iliah – the DNG format stands for “digital negative” which is a raw format file

  • Iliah Borg

    Dear Darlene,
    DNG is not always a raw format, it is also not exactly a format – it is a container; and yes, the expansion is an unfortunate misnomer. Better to say that DNG stands for DNG.

  • Guys please. We try to keep it friendly here and I’m glad Lamonte has taken the high road and will not reply again. I comment only so this ends here and to clarify things for readers.

    1 – DNG which is a raw format file, means digital negative. I’m not making this stuff up.
    2 – yes you can use a film negative different ways and make very different looking prints. Study Ansel Adams – he has printed Moonrise over Hernandez 100s of times, and it always looks different. I’ve been in museums where they had 6 different prints made by the same negative – some had a lighter sky, some had almost black.

    The point is that you cannot reprocess the actual film negative but you sure can make different outputs in the form of prints. The same is true of the digital version of negatives (raw or dng files).

    You cannot retake it or recreate it or alter the file – and in fact when you are processing the raw file you are not changing it at all you are just changing how the output comes out from that file. Only when you export to JPG do you have a saved result (in effect like making a print) Notice in LR it there is a “print to file” option in the Print module. The terms are similar and do serve similar functions. I did film for many years and did my own darkroom work. I can attest to this personally.

  • I guess you know better than Adobe who created it?

  • Iliah Borg

    Given that to err is human, and Adobe folks are also human – I do not see why they can’t be mistaken. For example, the whole AdobeRGB colour space is a result of a mistake.
    Yes, it is not a discussion – raw is not a negative. That’s a fact.

  • Iliah Borg

    Dear Darlene,

    One can also make very different prints from, say, tiff or jpeg. It is a norm in pre-press. Making different prints does not make the argument.

    There is nothing unfriendly in pointing out something which is incorrect; but some responses here are not friendly at all, which is natural.

    The good thing is that the readers now have a chance to understand what raw is a little better – it is a positive latent image, that can be developed differently any number of times.

    There are many reasons to shoot raw – one of them is that raw converters are constantly progressing, and so are our skills. Re-processing the old raw files allows to benefit from both those aspects. The difference often is no short of amazing.

  • Richard Leonard

    I think I will, thanks.

  • Alex

    You really should do your research into what DNG really is and what relation it has to a negative rather then point at Adobe and say they know better. What makes Adiobe an expert in anything related to negatives or let alone uncompromised solutions?

  • Well they created it (correct me if I’m wrong) and named it. Please do tell me what it really is then?

  • Will wait for the review πŸ™‚ Thanks.

  • Alex

    It still does not make it even raw let alone negative. Again please fo your research and as a clue that involves more than reading common facts or using Wikipedia. Without that all arguments here are just empty talks.

    Iliah has given you the starting point – dng is only the container format (yet another one) that is geared towards storing image data. It is neither negative nor raw (except very few cases for the latter).

  • Here’s the thing – I do not have time to research that, nor does it affect my ability to do photography. This is really highly technical information, way over most people’s heads, that isn’t needed to do the job. What you do need to know is how to use the files and what each of them are for, what purpose they serve. That is far more helpful IMO anyway. If you are into tech stuff then by all means dig deeper – for those that aren’t it’s really not crucial.

  • Alex

    Then why are you trying to argue the meaning of effectively technical terms if you have no desire to understand the details? This is unfortunately how all of these discussions start and die out and why there is confusion out there about raw, negatives, ISO definition, white balance, profiles etc.

  • Please tell us what is correct? I’d love to hear it.

  • Alex

    Tell you what exactly? Iliah did, you started the argument without doing research or getting more technical (as you expressed it yourself) and here we are.

    I did my research into raw files (for the software I wrote) and fair bit of dark room processing (back in 80s and 90s) and I tend to agree with Iliah raw is not negative. The argument aplied here that it is negative by association of negative requires to be developed is also wrong – once you have a negative it is already developed and fixed, it is not reversable and it does not need development to get the final image. The development of the negative from latent image itself does not also have the same visual degree of control as development of raw files does. Raw files as Iliah already said above can be developed many times with entirely different parameters – there simply no equivalent of this in negative processing.

  • Nick V

    Great article. I would also like to know if you could do an article on Database Software like Lightroom. Lightroom’s Database functionality is amazing, and would like to know if there is any competition in that field, free or paid.

  • Richard

    Amen to all of the votes for Darktable – my favorite.

  • You’re both right, I’m done arguing about it. Let’s move on please.

  • Mark Fullerton

    I have a Sony camera and use Capture One from Phase One. They have a free Basic edition and a paid Pro edition. As with any of these RAW editors it takes a while to get up to speed but the documentation is extremely useful. I got started by concentrating on one aspect of the editor and then gradually learned the other features over time.

    Unfortunately the YCbCr format it produces is not compatible with the Sony TV, so I use the batch converter in RAWTherapee to convert them to a 4:2:2 format.

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  • bushrat49

    The children arguing was a bit of a downer, but the article was pretty good. Sarah Hipwell and
    Darlene Hildebrand, I have a feeling you guys were being baited. I would just ignore them, the rest of us did. Once again, great article.

    One other thought, I am considering a digital image software called ACDSee Pro 8. I don’t have a great deal of money to spend, yet wanting something decent to use for my images using a Sony A100 DSLR camera. I never see any articles written about it’s features. I feel it may be a good product at a reasonable price. It’s not PS, but it seems to have enough of the normal features I’m looking for. And it it is RAW processing capable. Any chance of seeing a review on this apparent “stepchild” software. Thank you!


    thats perfect

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