Tri-X vs HP5 on iPhone: black and white with colour filters

26 September 2026

To get a Tri-X or HP5 look on iPhone, start from a clean monochrome develop of a RAW file. Pick a colour filter for how skies and skin render, then set the contrast and grain to suit the film. Tri-X means punchy contrast, deep blacks and prominent grain. HP5 means softer contrast and generous highlights. Below is what separates the two films, how colour filters work in black and white, and two original recipes you can shoot live.

Tri-X and HP5: two 400-speed films, two characters

Kodak Tri-X 400 is probably the most famous black and white film ever made, the default film of photojournalism for decades. Kodak's Tri-X 400 page talks about its "classic grain structure", edge sharpness, wide latitude and suitability for push processing. Photographers usually describe it as punchy. Blacks go deep, midtones have bite, and the grain is part of the picture rather than something to hide. Pushed a stop or two, it gets grittier still.

Ilford HP5 Plus is the British counterpart. Ilford's HP5 Plus page describes medium contrast, fine grain and wide exposure latitude, and says it "has been formulated to respond well to push-processing and can be rated up to EI 3200". At box speed it's softer and more forgiving than Tri-X. Highlights stay open, shadows stay grey rather than black, and the negatives print easily. People often choose HP5 when they want to push it, or when the light is hard to meter.

In practice, both films look the way they do partly because of the developer, the paper or the scan. The differences below are tendencies, not laws.

Colour filters in black and white

Black and white film records brightness, but it doesn't respond equally to every colour. For a century, photographers have put coloured glass over the lens to change which colours come out light and which come out dark. A filter lets its own colour through and holds back the opposite colour. Whatever it holds back comes out darker in the print.

• Yellow holds back some blue. Skies darken a little, and clouds separate from the sky. It's the everyday landscape and street filter.
• Orange does more of the same. Skies go noticeably darker, haze is cut, and brick and skin lighten.
• Red is the dramatic one. Blue sky goes nearly black, clouds stand out white, and shadows lit by blue sky go deep. Skin and lips lighten, sometimes too much.
• Green lightens foliage and darkens reds. Skin gains a little tone, and lips and blemishes darken. Some portrait photographers like it for faces because skin keeps its tone instead of going pale.

A digital filter does the same thing with arithmetic. A monochrome develop mixes the red, green and blue channels into one grey value. A "red filter" gives the red channel more weight and blue less, so blue sky comes out dark. With RAW there's one big difference from glass: the filter isn't fixed at the moment of exposure. You can shoot with red and change to green later.

Chobial's monochrome films have a B&W Filter control in the Color section, with presets for None, Yellow, Orange, Red and Green, or your own R/G/B weights from 0 to 1. The built-in films include Chobial B&W and three filtered versions: + Ye, + R and + G.

Recipe: Street 400

This is our own recipe for a Tri-X-type look. It starts from Chobial B&W + Ye, a fine-grained monochrome with deep blacks, and adds contrast and grit. Both recipes on this page are starting points. Adjust them against your own photos.

• Contrast up and Shadows down give the deep blacks and punchy midtones. Low Highlight Rolloff keeps the highlights bright rather than creamy.
• Local Tone Mapping 25% matters more in black and white than in colour. The iPhone's usual shadow lifting flattens a mono image into grey. Turning it down lets shadows go properly dark.
• Grain is the 35mm ISO 400 stock, set a little stronger and larger than the preset. The grain in Chobial follows a curve measured from a real camera's film renderings. It is strongest in the midtones and stays visible into the highlights, which is why a grey wall or a sky looks gritty, as it does on Tri-X. More in why digital grain looks fake.
• + Ye for everyday streets; + R for architecture against blue sky. For a pushed look, raise Contrast to +0.40 and grain Size to 1.6.

Recipe: Soft 400

This is our own recipe for an HP5-type look. It starts from plain Chobial B&W and opens up the tones.

• Lower contrast, lifted shadows and high Highlight Rolloff give HP5's open, printable tones. Skin and bright skies keep their detail.
• The custom filter weights lean slightly away from blue. Skies get a hint of separation, and green gets enough weight to keep foliage and skin from going muddy. For a stronger effect, switch to the Yellow or Green preset.
• Toning (the name Split Toning takes in mono) adds a faint warm cast like fibre paper. Set Amount to 0 for neutral.
• Grain stays at the stock preset for a calmer texture than Street 400.

Doing it in Chobial

1. Open Films (hold the film on the camera) and tap + › New Film. Start from Chobial B&W + Ye for Street 400 or Chobial B&W for Soft 400. The Make your own film tutorial covers each section.
2. Choose a preview photo with sky, skin and foliage in it, so you can see what the filter does. Enter the settings and hold the preview to compare.
3. Save. Load the film and the viewfinder shows black and white live. Seeing in tones instead of colours is half the point of shooting mono.
4. Use Zebra under DISP to keep highlights from clipping. It matters more in black and white because clipped areas turn to flat white patches. See manual controls.
5. Change your mind about the filter later: open the photo, choose the Film tool and tap Chobial B&W + R or + G. The RAW develops again, still in colour underneath.

Halation in black and white

You might expect to add halation only to colour films, but real black and white film halates too. Mono films have anti-halation layers, but bright point sources still glow. Chobial's halation works in monochrome films. There the glow is neutral grey rather than red-orange, at the same brightness. On Street 400, try the Subtle halation stock for night streets. Lamps and headlights get a soft neutral glow, much like a Tri-X frame of a lit street.

Other routes

The Photos app's Mono, Silvertone and Noir filters are free and fine for a quick conversion. Lightroom Mobile has black and white profiles and a mixer, but it's editing after the fact, one photo at a time. For a camera-style approach, see the Ricoh GR's Hi-Contrast B&W on iPhone. What Chobial adds is a black and white film you see live, on a RAW negative, with filters you can change later.

Kodak and Tri-X are trademarks of Eastman Kodak Company. Ilford and HP5 are trademarks of Harman Technology Limited. Chobial is not affiliated with either.

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