I know this place in NYC where I love developing film because the results are amazing. It's not cheap so I was wondering if the great colors come from the scan or if the developing can affect the colors.
Color film is fabricated by applying numerous light sensitive coats on a single support. The red sensitive coat is on the bottom followed by the green sensitive coat. Lastly, the blue sensitive coat is on top. It’s not that simple as just three coats, there are many intermediate coats plus a slow and fast coat for each primary color. When this multi-sandwich is developed, the fluids must infuse to reach the innermost layers. The infusion rate is a time/temperature operation. Any change will cause different layers to come to culmination or not. In other words, the final color balance is based on these variables. The standards are generally 1/6 f-stop ± for each layer. All of this is besides the any shifts that are induced depending on the time between exposure and processing. What I am telling you is, the variables are substantial, the color and density will vary somewhat between labs. Also film developed in the same lab on different days will show variations.
If you are asking about the quality of the film (negative), it is dependent on how it's processed thru the quality of the chemicals which is dependent on how well the chemicals are being replenished with newer batches. Slower volume labs have a higher rate of replenishments whereas larger volume labs have smaller rate of replenishment. This rate of replenishment is measured by a quality control negative srip sent thru the film processor on a daily basis to achieve the rate required.
If you are asking about the quality of the print, it also dependent on the printer used and print processor if it is process thru wet chemicals (old type) or Dry inkjet inks. Using the Wet Chemicals process quality is the same dependency as that of the film. Using a dry inkjet inks is also dependent on the printer and how many colors of ink used for that particular printer. The more color dyes or inks the better the reproduction of the colors are (wider gamma). When it's printed on dry inks, your film or negative has to be digitized, transfered to digital and the digitizing equipment also make a big difference on the quality of print produced. The more wide spectrum of gray or colors it can digitized, the better the quality of print will be. It all sums up to how much quality the Lab wants to put out and their technical skills in doing so. Every labs has a different standard of quality. Labs also has different type of customers, ie, amateurs, professionals, candid shots, etc.