Emulating analog film digitally Part 2 - Emulation process

There’s lot to choose from both free and commercial tools on the market who claims to mimic the look and feel of analog film. I have tested couple of them and the results are not too reassuring.


I tested one product and its emulation of Fuji Velvia 100. Picture on the left is a scan of real Fuji Velvia 100, second one is exactly the same scene shot with Sony A7 with default settings. The third one is interpretation of Velvia 100 from a commercial software. I don't know how their emulation was derived, but it´s quite clear they've never seen a picture of Fuji Velvia before. interpretation is not even close. I was able to do just the same by only editing the contrast in the RGB-curve

                     Velvia 100                                                      Sony A7                                                    Velvia 100 Emulation

At this stage it´s quite clear if I want the look of film digitally I have to do it myself, I can´t afford to buy every piece of software and test them separately if someone happens to get it right. For the process of film emulation I need the following tools:

• Proper digital camera
• Old analog SLR (mine is Olympus OM 20) with a lens without color cast, some older lenses develop a color cast while ageing.
• Film you want to emulate. Shoot the same scene with digital and analog. Different scenes, lighting, high contrast, low contrast, color targets etc.
• Color checker and many shot of it 
• possibility to scan the film with unaltered colors. I wrote about this in my previous post.
• Software to tweak colors. I used Adobe Photoshop and Camera Raw (Lightroom) and my recipe is based on these tools. 

The process

Proper emulation of the film involves emulation of:

• Dynamic latitude and contrast (tone curve)
• color response (RGB curves, white balance and color balance)
• Details (grain and sharpness)
• Scratches and dust (optionally) 

Start with a pictures taken both with film and digital camera from the color target in a daylight illumination or flash. Both pictures shall have the exact same exposure. Read the color values in all patches from the analog picture, It´s easy with Photoshop or Camera Raw. You need both RGB-values and Lab-values. Both pictures must be in the same color space; sRGB, Adobe RGB or ProPhoto. It doesn't matter which color space, but the color space must always be identical in all pictures. RGB values are different in different color spaces. Film is hardcoded to the daylight white balance (5500 K), so the digital picture must be adjusted according to that. We're trying to emulate the look of the film, not the scene. 

Target Reference - Velvia 100

Unedited picture from the same scene with digital camera

Read the Lab-values from the six gray patches in the digital picture. Adjust the tone of RGB channel in Camera Raw so that the L: in the Lab channel is identical with the analog picture. L: channel does not contain any color information only lightness. You should now have some kind of s-shaped tone curve. Then change the readings from Lab to RGB and adjust all the three channels individually so that all RGB channel values are identical to the analog picture. Much of the color information in analog film is "hidden" in the gray patches – film is never completely white balanced. When this step is completed, your digital picture should already be very close to the target. Color response should now be almost accurate and only some remaining colors may still need some extra tweaking, but you can leave it here if you want because curves responds to the light in a “right” way and won't twist colors in different lighting situations. 

Digital picture after the modification of RGB-curves

Next step is tweak with HSL sliders for the remaining colors to match. Most important is the hue. Hue tells what color the color is. This is a time consuming process and it´s impossible to get a 100 % match. More is not better here because too many/extreme corrections will only twist the colors and the preset will be less universal. Try to keep individual color modifications to the minimum. In theory you should be able to mimic the look of the film only by adjusting the RGB curves. Film is different from digital camera in way that the color response is not linear i.e. the hue of the individual color will change along with exposure.


I also tried to make camera specific DNG profiles with DNG profile editor but it didn’t gain any better results.


Then compare analog/digital shots from different scenes and lighting and tweak even more. This is rather an artistic process than scientific. But don't overdo it, every scene will not be picture-perfect no matter how you tweak it.


When the colors are ok you can add the film grain. In Lightoom/Camera Raw just inspect the grain in the analog picture and add grain so that the amount, size and roughness will match. Velvia 100 has the values: Amount: 12 Size: 42 Roughness: 76. If you want the perfection, you can copy the grain from a neutral area in the analog picture and blend it in a layer in Photoshop, but I don’t think anyone will see any difference and the process is time consuming. Graininess in film increases as density increases and film grain is not monochromatic. Too much artificial grain will tell it´s “photoshopped”.


My emulation of Velvia came across better than I expected and it works well in wide variety of lighting situations. It's no trick to fix one photo to match another, but automatizing the process is. Of course not every color is spot on because films response to light is not linear, but the feeling of Velvia shines through and it’s hard to tell difference especially if you don't have a reference to compare with.


It´s a mystery to me why these commercial film emulating products doesn´t perform any better than they do. Is it lack of skills or improper scanning or what?


Here are some examples I compared my interpretation of digital film with the original and a well known company who provides presets to mimic film:

Velvia                                Straight out of camera                   My version                                   Commercial version

I also did preset for Kodak Ektar negative film:

Kodak Ektar                                                My version                                                   Commercial version

In the last picture pair one is real Velvia and the other one is my simulation of it. It´s hard to tell the difference:

This is Velvia                              Or this?